GIFT   OF 


GUIDE 


TO 


PREPARATION  WORK 


IN 


INORGANIC  CHEMISTRY 


FOR 


STUDENTS  OF 
CHEMISTRY  AND  PHARMACY 


DR.  REINHART  BLOCHMANN 

Professor  at  the  University  of  Konigsberg 


With  Numerous  Illustrations 


AUTHORIZED  TRANSLATION  BY 

JAS.    LEWIS    HOWE 

Washington  and  Lee  University 


DEPARTMENT  OF  CHEMISTRY 

WASHINGTON  AND  LEE  UNIVERSITY 

LEXINGTON  VIRGINIA 


GUIDE 


TO 


PREPARATION  WORK 


INORGANIC  CHEMISTRY 


FOR 


STUDENTS  OF 
CHEMISTRY  AND  PHARMACY 


BY 


DR.  REINHART  BLOCHMANN 

Professor  at  the  University  of  Konigsberg 


With  Numerous  Illustrations 


AUTHORIZED  TRANSLATION  BY 

JAS.    LEWIS    HOWE 

Washington  ^nc  Lei.  University 


DEPARTMENT  OF  CHEMISTRY 

WASHINGTON  AND  LEE  UNIVERSITY 

LEXINGTON  VIRGINIA 


i'j 


Copyright,  1902, 
By  JAS.  LEWIS  HOWE. 


'••*    c%  •      *•  * -  * ,  • '   ' 

1  *»J       .  V  !  :/ ! 


Printed  by  J.  P.  BELL  CO.,  Lynchbur?,  Va. 


PREFACE. 


This  little  book  is  intended  to  serve  as  a  first  guide  to  students 
of  chemistry  and  pharmacy  in  inorganic  preparation  work;  it 
assumes  that  by  practical  work  the  student  has  already  acquired 
a  good  knowledge  of  analytical  chemistry. 

The  rational  preparation  of  chemical  compounds  must  always 
rest  upon  the  stoichiometric  proportions  of  the  reacting  substances. 
The  course  of  the  reaction  is  given  briefly  under  each  prepara- 
tion and  then  a  definite  exercise  is  assigned.  The  quantities  of 
all  the  materials  used  are  to  be  determined  and  weighed  by  the 
student  himself.  Where  on  practical  grounds,  or  for  other 
reason,  a  departure  from  the  stoichiometric  quantities  seems  to 
be  demanded,  attention  is  called  to  it  and  the  reason  sought. 
Hence  the  student  cannot  avoid  a  careful  quantitative  study  of 
those  chemical  processes  which  he  carries  out. 

The  amount  of  substance  which  can  be  obtained,  or  the  ratio 
in  which  this  stands  to  the  theoretical,  is  given,  for  comparison 
with  the  results  obtained  by  the  student.  It  is  here  assumed 
that  the  process  is  carried  out  to  completion.  Wherever  it  has 
seemed  necessary,  attention  has  been  called  to  the  indications  by 
which  the  end  of  the  operation  may  be  recognized,  and  also  to 
the  various  phenomena  during  the  reaction,  which  serve  as  a 
guide  for  its  proper  course. 

•  When  it  is  intended  to  prepare  a  certain  compound,  this  can 
be  accomplished,  in  very  few  cases,  by  the  direct  union  of  the 
materials  involved  (as  in  case  of  the  action  of  ferrous  sulfate, 
sulfuric  acid,  ammonia  and  nitric  acid  to  form  iron  alum), 
without  the  formation  of  by-products.  In  most  cases  by-products 
are  formed;  indeed,  certain  branches  of  chemical  industry  are 

239429 


IV  PREFACE. 

industrially  possible  only  on  account  of  the  value  of  these  by- 
products. In  all  cases  where  by-products  of  value  are  formed, 
the  recovery  of  these  in  useful  form  is  carried  out,  in  order  that 
the  student  may  early  become  accustomed  to  the  consideration 
of  a  reaction  from  every  standpoint. 

In  the  selection  of  preparations  three  points  have  been  taken 
into  account: 

1.  As  raw  materials  are  used, 

(a)  Natural  products  such  as  barite,   cryolite,  stib- 
nite,   etc.,    or  products  of  the  larger  chemical 
industries,   as  sulfuric  acid,   hydrochloric  acid, 
soda,  saltpeter,  etc.; 

(b)  The   chief  products  or  the  by-products  of  the 
previous  preparations. 

The  cost  of  the  raw  materials  for  carrying  out  this  preparation 
work  is,  therefore,  low,1  and  the  preparation  of  large  quantities 
of  worthless  material  is  avoided. 

2.  The  length  of  time  which  the  single  operations  require 
without  interruption  rarely  exceeds  an  ordinary  labo- 
ratory period  of  two  or  three  hours. 

The  statement  of  the  time  in  each  case  renders  possible  the 
best  disposition  of  it  by  the  student. 

3.  The  preparations  have   been   so   chosen  as   to   give 
opportunity  for  the  student  to  become  acquainted  with 
the  most  varied  chemical   processes,    the   most  fre- 
quently used  operations,  and  many  easily  prepared 
and  approved  forms  of  apparatus. 

As  regards  the  presentation  of  the  subject,  under  each  prepa- 
ration is  first  given  a  list  of  the  necessary  raw  materials,  next  a 
short  sketch  of  the  course  of  the  chemical  reactions  involved, 


1  The  cost  of  the  raw  materials  for  carrying  out  all  the  preparations 
given  in  this  book  is  about  $1.50. 


PREFACE.  V 

and  then  the  exercise  is  definitely  stated.  The  description  of 
the  method  of  carrying  out  the  operation  and  of  setting  up  the 
apparatus  to  be  used,  is  given  in  the  earlier  preparations  with 
great  fulness.  In  the  later  exercises,  assuming  an  acquired 
facility,  the  descriptions  are  much  briefer.  A  paragraph  as  to 
the  amount  of  the  product,  its  properties  and  tests,  concludes 
each  section. 

R.  BLOCHMANN. 

Konigsberg,  January,  1895. 


For  several  years  Blochmann's  Anleitung  zur  Darstellung 
chemischer  anorganischer  Praparate  has  been  used  in  my 
classes  and  has  fully  demonstrated  its  value. 

The  translation  is  made  from  a  copy  specially  corrected  and 
annotated  by  the  author.  J.  L.  H. 

Washington  and  Lee  University, 

Lexington,  Va.,  August,  1902. 


CONTENTS. 


PREPARATIONS. 

1.  Hydrochloric  Acid 3 

2.  Ammonia 7 

3.  Sodium  Ammonium  Sulfate 11 

4.  Nitric  Acid 12 

5.  Fuming  Nitric  Acid 14 

6.  Soda  and  Alumina  from  Cryolite 16 

V  7.     Alum 18 

8.  Silver  Nitrate  from  Coin  Silver 19 

9.  Liquid  Sulfur  Dioxid 21 

A.  Precipitation  of  Copper  from  Copper  Sulfate 22 

B.  Preparation  and  Condensation  of  Sulfur  Dioxid 23 

10.  Iron  Ammonium  Alum 27 

11.  Potassium  Nitrite 29 

\  12.     Phosphoric  Acid 32 

13.  Disodium  Phosphate,   Sodium  Ammonium   Phosphate,    Pyro- 

phosphoric  Acid  and  Metaphosphoric  Acid 35 

A.  Disodium  Phosphate 35 

B.  Sodium  Ammonium  Phosphate 36 

C.  Pyrophosphoric  Acid 36 

D.  Metaphosphoric  Acid 37 

14.  Lead  Peroxid 38 

15.  Antimony  Trichlorid 40 

16.  Fluosilicic  Acid 43 

17.  Crystallized  Silicon 46 

18.  Recovery  of  Tin  from  Tinplate 47 

19.  Carbamid  (Urea) 49 

20.  Barium  Nitrate..  51 


Vlll  CONTENTS. 

21.  Hydrated  Barium  Peroxid 52 

22.  Hydroxylamin  Hydrochlorid 55 

23.  Phosphorus  Pentachlorid 57 

24.  Monochlorosulfuric  Acid 59 

25.  Amidosulfonic  Acid 61 

A.  From  Monochlorosulfuric  Acid 61 

B.  From  Hydroxylamin 64 

TABLES. 

Atomic  Weights  and  Multiples 69 

Specific  Gravity  of  Hydrochloric  Acid 70 

Specific  Gravity  of  Nitric  Acid 70 

Specific  Gravity  of  Concentrated  Sulfuric  Acid 71 

Specific  Gravity  of  Aqueous  Ammonia 71 

Solubility  of  Certain  Salts  (in  100  parts  water) 72 

Solubility  of  Certain  Salts  (water  required  for  1  part) ........  73 


PREPARATIONS 


i.  Hydrochloric  Acid. 

( By-product :  Hydrogen  sodium  sulfate. ) 

Raw  Materials :  Common  salt,  concentrated  sulfuric  acid,  con- 
centrated hydrochloric  acid  (commercial). 

By  the  action  of  concentrated  sulfuric  acid  on  common  salt  at 
ordinary  temperature  or  at  moderate  heat,  hydrogen  sodium 
sulfate  is  formed,  in  addition  to  the  hydrochloric  acid,  and  this 
is  the  case  even  when  the  salt  is  in  excess  : 

(1 )  2NaCl  +  H2SO.  =  HCl  +  HNaSO,  +  Na  Cl. 

It  is  only  at  high  temperatures  that  the  hydrogen  sodium 
sulfate  reacts  with  the  excess  of  sodium  chlorid,  according  to 
the  reaction  : 

(2)  HNaSO,  +  NaCl  =  Na2SO,  +  HCL 

On  a  small  scale1  hydrochloric  acid  is  prepared  according 
to  the  reaction: 

(3)  Na  Cl  -f  H,SO,  =  HCl  +  HNaSO.. 

Exercise  :  To  prepare  500  grams  of  aqueous  solution  of  hydro- 
chloric acid  containing  20  per  cent,  of  HCl. 

The  apparatus  (see  Fig.  1)  consists  of  a  flask  A,  which  rests  on  a  sand 
bath;  a  wash  bottle  B  ;  a  retort  (7,  which  contains  the  water  in  which 
the  hydrochloric  acid  is  absorbed.  The  retort  stands  with  its  body  in  a 
dish  holding  about  3  liters,  and  is  held  by  the  clamp  of  a  retort  stand 
loosely,  so  that  it  can  be  rotated  about  the  axis  of  its  neck. 

The  flask  A  is  round-bottomed,  holding  about  2  liters.     Its  mouth  is 


1  On  a  large  scale  hydrochloric  acid  is  made  in  a  furnace  of  firebrick, 
and  the  reaction  involved  is  : 

ZNaCl  +  H2SOi  =  Na2SOt  +  2HCI, 

since  this  process  is  more  economical  and  it   is   desired  to   obtain   sodium 
sulfate,  Na2SOi. 


4 


HYDROCHLORIC   ACID. 


closed  by  a  well-fitting  cork  with  two  holes;  through  one  of  these  passes  a 
safety  funnel  a,  and  through  the  other  the  delivery  tube  6.  These  tubes 
must  fit  air-tight  in  the  cork.  It  is  well  to  cut  the  lower  end  of  the  de- 
livery tube  b  diagonally  (and  also  that  of  the  tube  e),  or  to  file  a  small  hole 
in  the  tube  near  its  end,  so  that  the  drops  which  collect  here  shall 
not  be  carried  along  by  the  stream  of  gas. 

The  wash  bottle  B  is  a  three-necked  Wolff  bottle,  holding  about  0.5 
liter,  and  should  be  about  twice  as  high  as  its  diameter.  The  necks  are 
closed  with  perforated  corks  through  which  pass  the  inlet  tube  c,  the 
delivery  tube  e,  and  the  safety  tube  d ;  the  last  prevents  the  liquid  in  C 


Fig.  1.     Apparatus  for  the  preparation  of  hydrochloric  acid. 

from  being  sucked  back  into  B.  (In  the  place  of  a  Wolff  bottle  a  flask 
can  be  used,  fitted  with  a  cork  having  three  perforations. )  The  retort 
should  hold  about  400  to  450  cc,  and  the  neck  should  be  large  enough  to 
hold  all  the  liquid  which  can  be  driven  out  by  the  air  when  the  flask  is 
placed  diagonally.  The  tube/,  which  is  slightly  bent  at  its  lower  extremity, 
is  supported  by  a  cork,  with  a  small  groove  cut  lengthwise  on  its  edge,  in 
order  not  to  close  the  retort  completely. 

The  tubes  b  and  c  are  connected  by  a  short  rubber  tube,  the  tubes  e  and 
/  by  one  somewhat  longer. 

Operation  :    After  the  apparatus  has  been  tested  and  found 
air-tight,  the  flask,  the  wash  bottle,  and  the  retort  are  weighed. 


HYDROCHLORIC   ACID.  5 

The  necessary  quantity  of  distilled  water  is  placed  in  the  retort;1 
the  wash  bottle  is  filled  one-fifth  full  of  (commercial)  concen- 
trated hydrochloric  acid,  whose  specific  gravity  has  been  deter- 
mined by  a  hydrometer,  and  again  weighed.2  The  amount  of 
concentrated  sulfuric  acid  to  be  used  is  calculated  according  to 
equation  (3),  account  being  taken  of  its  specific  gravity,  and  the 
acid  is  diluted  with  one-fifth  its  weight  of  water,  (How  ?  Use 
care !  )  that  the  evolution  of  gas  may  not  be  too  violent.  When 
the  acid  is  cold  it  is  poured  through  the  safety  funnel  a  into 
the  flask,  in  which  the  requisite  quantity  of  common  salt  has 
been  already  placed.  The  retort  into  which  the  gas  is  led  is 
at  first  set  in  such  position  that  the  air  expelled  by  pouring  in 
the  acid  shall  not  collect  in  its  body,  but  escape  by  the  neck. 
By  shaking  the  flask  gently  a  uniform  mixture  of  acid  and  salt 
is  obtained,  and  then  the  flame  under  the  sand  bath  is  lighted. 

As  soon  as  white  fumes  are  seen  in  the  neck  of  the  retort,  and 
the  clicking  sound  occasioned  by  the  absorption  of  the  hydro- 
chloric acid  is  heard,  the  retort  is  turned  so  that  the  gas  bubbles 
all  come  up  into  its  body.  A  rapid  evolution  of  hydrochloric  acid 
now  takes  place,  which  may  be  increased  by  more  heat  under  the 
flask ;  care  must,  however,  be  taken  that  the  contents  of  the  flask 
do  not  froth  over.  If  the  portion  of  the  retort  not  under  water 
is  covered  with  a  wet  cloth,  there  is  no  danger  of  an  appre- 
ciable loss  of  hydrochloric  acid  through  incomplete  absorption. 
Such  a  loss  can  be  recognized  by  holding  a  glass  rod  wet  with 
ammonia  or  a  strip  of  blue  litmus  paper  at  the  mouth  of  the 
retort.  If  the  pressure  in  the  retort  increases  during  the  oper- 
ation so  much,  that  the  column  of  liquid  in  the  safety  tube  a  is 
insufficient  to  maintain  an  equilibrium,  the  pressure  can  be 
decreased  by  slightly  turning  the  retort. 

The  end  of  the  reaction  is  recognized  by  the  following  phe- 

1  Compare  footnote  to  page  6. 

2  If  water  were  placed  in  the  wash  bottle,  so  much  hydrochloric  acid 
would  be  absorbed  that  the  product  would  not  reach  the  required  strength. 


6  HYDROCHLORIC   ACID. 

nomena  :  the  frothing  in  the  flask  ceases  ;  the  tube  leading  to 
the  wash  bottle  becomes  hot  (why  ?) ;  the  liquid  in  the  retort 
sucks  back  through  the  tube  / ;  air  bubbles  enter  the  wash 
bottle  by  the  safety  tube  d.  The  flame  under  the  sand  bath  is 
now  turned  down  and  the  connection  between  A  and  B  broken; 
the  flame  is  raised  again  and  the  gas  given  off  is  tested.  If 
no  fumes  of  ammonium  chlorid  are  formed  about  a  glass  rod 
moistened  with  ammonia,  the  operation  may  be  considered  at 
an  end. 

Time  of  Operation  :  About  two  hours. 

Yield :  To  find  the  yield  of  hydrochloric  acid,  the  weight 
and  specific  gravity  of  the  contents  of  the  retort  and  of  the 
wash  bottle  must  be  determined.  Calculation  shows  whether 
more  or  less  hydrochloric  acid  is  present  in  the  wash  bot- 
tle than  at  the  beginning  of  the  operation;  an  excess  is  to 
be  added  to  the  hydrochloric  acid  found  in  the  retort,  a  minus 
quantity  is  to  be  deducted.  If  the  operation  has  been  carefully 
carried  out,  from  90  per  cent,  to  92  per  cent,  of  the  theoretical 
quantity  should  be  obtained.  Generally  the  product  contains 
only  18  per  cent,  to  19  per  cent,  of  hydrochloric  acid.1 

Test :  The  product  obtained  will  be  free  from  arsenic  if  the 
sulfuric  acid  used  was  itself  free.  The  product  should  be  free 
from  sulfuric  acid  and  should  leave  no  residue  on  evaporation. 


By-product  :  Hydrogen  Sodium  Sulfate,  HNaS04. 

The  contents  of  the  flask  solidify  on  cooling  to  a  crystalline 
mass.  To  this  is  added  its  weight  in  water  and  all  is  brought 
to  solution  on  a  water  bath.  Filter  and  evaporate  on  the  water 
bath  in  a  porcelain  dish  until  a  crystalline  scum  begins  to  form 

1  To  ensure  the  preparation  of  20  per  cent,  acid,  not  all  the  calculated 
amount  (400  cc)  of  water  should  be  placed  in  the  retort,  but  a  portion 
(say  50  cc)  reserved.  A  stronger  acid  will  then  be  obtained,  which  may 
be  diluted  to  exactly  20  per  cent. 


AMMONIA. 


on  the  surface.  Then  heat  the  dish  with  free  flame  over  wire 
gauze,  stirring  constantly  until  all  frothing  has  ceased.  The 
temperature  of  the  fused  mass  will  now  be  about  250°.  If  the 
drop  which  adheres  to  the  thermometer  bulb  be  shaken  on  to  a 
glass  plate,  it  should  solidify  at  once  to  a  hard  mass,  upon  which 


Fig.  2.     Apparatus  for  Casting  in  Sticks. 

the  thumb  nail  makes  no  impression.  The  contents  of  the  dish 
are  then  either  cast  in  an  iron  mould  (Fig.  2)  or  poured  out 
upon  a  smooth  surface. 

Yield  :   95  per  cent,  of  the  theoretical  amount. 


2.   Ammonia. 

(By-product:   Granulated  Calcium  Chlorid.) 

Raw  Materials :  Ammonium  chlorid  (sal  ammoniac),  lime, 
concentrated  ammonia. 

Calcium  hydroxid  liberates  ammonia  from  ammonium  chlorid : 

(1 )  2NHi  Cl  +  Ca(  OH\=  2NH,  +  Ca  C12  +  2H.  0. 
Calcium  hydroxid  is  prepared  from  lime : 

(2)  CaO+H20=  Ca(OH)2. 


8  AMMONIA. 

Exercise  :  To  prepare  500  grams  of  10  per  cent,  aqueous 
solution  of  ammonia. 

Apparatus :     The  same  as  in  Exercise  1. 

Operation:  Since  lime  contains  not  only  magnesia,  ferric 
oxid,  etc.,  but  also  more  or  less  water  and  carbonic  acid 
(derived  from  the  air),  it  is  necessary  in  preparing  the  calcium 
hydroxid  to  use  20  per  cent,  more  freshly  burned  lime  than  is 
required  by  equation  (1).  The  lime  is  placed  in  a  porcelain 
dish  and  over  it  is  poured  the  quantity  of  water  demanded  by 
equation  (2).  The  water  which  is  lost  through  vaporization  by 
the  heat  of  slaking  is  to  be  replaced ;  this  is  easily  accomplished 
if  the  dish  was  weighed  while  empty.  After  slaking,  the  lime 
should  fall  to  a  powder  and  feel  dry  to  the  touch.  The  time 
required  depends  upon  the  quality  of  the  lime ;  in  general  two  or 
three  hours,  including  the  time  for  the  cooling  of  the  lime,  will 
be  sufficient. 

After  examination  has  shown  that  the  apparatus  is  air-tight, 
the  required  quantity  of  distilled  water  *  is  placed  in  the  retort2 
and  about  100  grams  of  ammonia  (sp.  gr.  0.945  to  0.960)  is 
placed  in  the  wash  bottle.  (The  exact  weight  and  specific 
gravity  of  the  ammonia  used  must  be  determined!)  Pour 
into  the  flask  the  quantity  of  slaked  lime  and  ammonium 
chlorid  required  by  equation  (1)  and  wash  down  the  neck 
and  sides  of  the  flask  with  a  quantity  of  water  sufficient 
to  dissolve  at  100°  all  the  ammonium  chlorid  used.  Close 
the  flask  quickly,  mix  the  contents  by  shaking  and  warm 
upon  the  sand  bath.  The  retort  should  be  so  placed  that 

1  The  experience  obtained  in  carrying  out  Exercise  1  shows  that  in 
order  to  prepare  a  10  per  cent,  ammonia  solution  it  is  best  to  reserve  some 
50  to  100  grams  of  the  450  grams  of  water  required  by  theory.     A  some- 
what stronger  solution  than  10  per  cent,  may  then  be  expected  and  this 
can  be  diluted  as  demanded. 

2  Accuracy  in  carrying  out  this  exercise  is  largely  dependent  upon  the 
use  of  a  retort  of  the  proper  size.     There  must  be  room  for  all  the  water 
used  in  the  body  of  the  retort  when  it  is  placed  in  its  usual  position. 


AMMONIA.  9 

the  bubbles  of  air  which  enter  it  rise  into  its  body.  As 
soon  as  the  ammonia  begins  to  be  absorbed,  which  is  evident 
from  the  crackling  noise,  the  retort  should  be  freed  from  air 
by  rotating  it,  and  should  then  be  firmly  clamped  in  position. 
This  reduces  the  pressure  by  lessening  the  height  of  the  column 
of  liquid  in  the  neck  of  the  retort.  From  time  to  time  the  in- 
creasing pressure  in  the  retort  may  be  regulated  by  a  proper  rota- 
tion. The  retort  is  to  be  kept  cool  as  in  Exercise  1.  If  the  ves- 
sel holding  the  retort  contains  three  liters  of  water,  this  water 
will  not  rise  in  temperature  more  than  five  to  ten  degrees  during 
the  operation.  The  flame  under  the  sand  bath  should  be  regu- 
lated so  that  the  contents  of  the  flask  boil  briskly.  The 
contents  of  the  wash  bottle  become  more  and  more  heated  owing 
to  the  water  which  distils  over,1  and  increase  decidedly  in 
volume. 

The  end  of  the  operation  is  recognized  by  the  tendency  of 
the  liquid  in  the  retort  to  rise  in  the  delivery  tube.  When  this 
occurs,  the  heating  is  to  be  continued  for  half  an  hour,  and  then 
the  gases  which  escape  from  the  flask  on  breaking  its  connection 
with  the  wash  bottle  are  to  be  tested.  If  no  decided  fumes  of 
ammonium  chlorid  appear,  when  a  glass  rod  moistened  with 
hydrochloric  acid  is  held  in  the  escaping  gas,  the  operation  is 
over. 

Time  of  Operation  :  About  three  hours. 

Yield  :  The  calculation  of  the  product  is  carried  out  as  in 
Exercise  1.  By  careful  work  it  is  possible  to  obtain  95  per 
cent,  of  the  theoretical  amount. 

Test  :    The  product  should  leave  on  evaporation  no  residue. 


By-product:   Granulated  Calcium  Chlorid,  CaCl2. 

While  still  warm  the  contents  of  the  flask  should  be  poured 


1  During  the  operation  about  150  grams  of  water  distill  over  into  the 
wash  bottle. 


10  AMMONIA. 

off  from  the  lumps1  generally  present  into  a  porcelain  dish,  and 
then  .boiled  with  constant  stirring  until  the  vapors  given  off 
cease  to  redden  blue  litmus  paper.  The  contents  of  the  dish 
are  then  diluted  (with  great  caution!)  with  about  500  cc  of 
water,  poured  into  a  beaker  glass  and  allowed  to  settle  over 
night.  If  the  supernatant  liquid  is  colored,  the  iron  pres- 
ent is  to  be  completely  oxidized  by  adding  a  few  grams  of 
bleaching  powder,  stirred  up  with  a  little  water,  and  after- 
ward neutralizing  the  liquid  with  hydrochloric  acid.  If  the 
liquid  accidentally  becomes  acid,  neutralize  with  lime  water. 
After  sedimentation,  filter  the  colorless  liquid  through  a  cor- 
rugated filter  [or  on  a  Hirsch  funnel  by  suction]  and  evapo- 
rate on  a  water  bath  in  a  porcelain  dish  until  the  liquid  no 
longer  decreases  in  volume.8  Now  heat  over  a  wire  gauze  with 
constant  stirring  until  the  contents  of  the  dish  have  become  solid, 
and  then,  removing  the  wire  gauze,  continue  the  heating  until  a 
cold  piece  of  glass  held  over  the  dish  shows  no  more  deposition 
of  water. 

The  dehydrated  calcium  chlorid  is  very  hygroscopic,  and 
hence  is  used  for  drying  gases,  for  the  quantitative  determina- 
tion of  water  in  elementary  analysis,  etc.  It  is  advisable  to 
break  up  the  lumps  at  once  and  to  fill  the  prepared  tubes. 

For  this  purpose  empty  the  contents  of  the  dish  while  hot 
into  a  porcelain  mortar,  break  up  the  larger  lumps  into  pieces 
the  size  of  a  pea,  and  screen  off  the  powder,  all  these  operations 
being  carried  out  as  rapidly  as  possible.  It  is  best  to  use  two 
sieves  with  different  sized  holes,  so  selected  that  pieces  of  the 
desired  size  will  pass  one  sieve,  but  not  the  other.  In  the 
enlargement  of  the  calcium  chlorid  tube  a  little  plug  of  asbestos 
or  glass  wool  is  placed  and  then  the  calcium  chlorid  poured  in ; 


out. 


OH 

a 

2  If  the  liquid  is  allowed  to  cool  at  this  stage,  CaCl2,6aq  crystallizes 


1  These  lumps  consist  chiefly  of  calcium  oxy chlorid,       ^ 


SODIUM   AMMONIUM   SULFATE.  11 

when  nearly  full  another  wad  of  asbestos  or  glass  wool  is  added 
and  the  tube  tightly  stoppered. 

If  the  calcium  chlorid  tube  is  to  serve  for  quantitative  work,  it  is 
necessary  to  lead  a  stream  of  dry  carbon  dioxid  through  it,  in  order  that 
the  calcium  oxychlorid  which  is  always  formed  in  small  quantities  at  high 
temperatures,  may  be  changed  into  the  neutral  salt : 


3.    Sodium  Ammonium  Sulfate. 


Raw  Materials:    Hydrogen  sodium  sulfate,  ammonia. 
The  formation  of  this  salt  proceeds  according  to  the  equation  : 
HNaSO,  +  NH,  =  NaNH.SO,. 

Exercise:  To  make  sodium  ammonium  sulfate  from  the  hydro- 
gen sodium  sulfate  obtained  as  a  by-product  in  Preparation  1, 
and  ammonia  of  sp.  gr.  0.88-0.90,  using  such  quantities  of 
ammonia  and  water  that,  after  the  mixture  has  cooled,  100  grams 
of  double  salt  shall  crystallize  out  without  further  evaporation. 

Operation  :  In  a  round-bottomed  liter  flask  place  whatever 
quantity  of  hydrogen  sodium  sulfate  is  at  hand,  with  the 
necessary  amount  of  water,  calculated  with  due  regard  to  the 
water  present  in  the  ammonia  which  is  to  be  used.  As  soon  as 
most  of  the  salt  has  dissolved  set  aside  about  10  cc  of  the  solution, 
and  then  add  with  great  care  the  requisite  amount  of  ammonia 
to  the  contents  of  the  flask.  The  solution  will  become  heated 
(to  about  80°C.)  and  will  have  an  alkaline  reaction.  If  it 
becomes  cloudy,1  filter  into  a  porcelain  dish.  Then  add  with 
constant  stirring  enough  of  the  solution  which  has  been  set  aside 


1  In  consequence  of  the  separation  of  ferric  hydroxid,  alumina, 
magnesia  or  other  impurities  contained  in  the  salt  or  the  sulfuric  acid  used 
in  making  the  hydrogen  sodium  sulfate. 


12  NITRIC   ACID. 

to  render  the  whole  neutral  in  reaction.  Set  in  a  cool  place  for 
crystallization. 

Sodium  ammonium  sulfate  is  apt  to  form  supersaturated  solu- 
tions, hence  it  often  happens  that  even  after  standing  several 
days  no  salt  crystallizes  out.  In  such  a  case  evaporate  a  few 
drops  of  the  solution  upon  a  watch  glass  until  crystals  appear, 
and  sow  these  in  the  supersaturated  solution. 

Properties:  Khombic  crystals;  one  part  of  NaNH.SO.,  2aq. 

ml  J.  4  4*  Z 

dissolves  in  2  1-7  parts 'of  water  at  15°. 


4.    Nitric  Acid. 

(By-product:     Hydrogen  potassium  sulfate,  HKSO±.} 
Raw  Materials:    Saltpeter  and  concentrated  sulfuric  acid. 
The  preparation   takes    place    according   to    the    following 
equation : 

KNO,  +  H,SO,  =  HNOS  +  HKSO,. 

Exercise :     To  prepare  100  grams  HNOy 


Fig.  3.     Preparation  of  Nitric  Acid. 

The  Apparatus  consists  of  a  retort  A  and  a  round-bottomed  flask  J5, 
which  are  fitted  to  each  other  as  shown  in  Fig.  3.  The  retort  rests  on  a 
sand  bath  over  a  Fletcher  burner,  C.  The  flask  is  placed  in  a  dish  of 


NITRIC   ACID.  13 

water  to  keep  it  cool,  and  is  supported  by  a  stand  to  which  the  neck  is 
clamped. 

The  body  of  the  retort  should  hold  about  0.7  to  0.8  liter  and  the  flask 
about  a  liter.  The  retort  projects  into  the  flask  so  far  that  when  the  neck  of 
the  flask  closes  tightly  around  the  neck  of  the  retort,  the  lower  end  of  the 
latter  reaches  the  middle  of  the  flask. 

If  the  dish  in  which  the  flask  rests  holds  about  3  liters  of  water  for 
cooling,  it  will  not  be  necessary  to  renew  the  water  during  the  operation. 

Operation :  Place  the  saltpeter  in  the  dry  retort  and  add 
the  required  amount  of  concentrated  sulfuric  acid  through  a 
funnel  whose  lower  end  reaches  the  body  of  the  retort.  Be 
careful  in  withdrawing  the  funnel  not  to  touch  the  sides,  and 
also  that  no  saltpeter  adheres  to  the  neck.  On  agitating  the 
retort  the  contents  become  warm. 

Fit  retort  and  flask  together,  place  under  a  hood,  fill  the 
porcelain  dish  with  water  and  heat  the  sand  bath  with  a  small 
flame.  At  the  beginning  of  the  operation  yellowish  brown 
fumes  appear,  owing  to  the  reduction  of  the  nitric  acid  by  the 
dust  present  in  the  saltpeter;  at  the  end  of  the  reaction  similar 
fumes  are  given  off  from  the  decomposition  of  nitric  acid  by 
heat.  The  flame  should  be  so  regulated  that  the  fumes  shall 
condense  completely  in  the  neck  of  the  retort  and  in  the  flask ; 
this  can  be  assisted  by  covering  the  flask  with  a  wet  cloth. 
When  the  contents  of  the  retort,  at  first  partly  at  least  liquified, 
have  become  solid  again,  the  heat  should  be  increased.  The 
end  of  the  operation  is  recognized  by  the  fact  that  drops  fall 
into  the  flask  only  occasionally,  and  the  fumes  in  the  retort 
become  darker.  The  sand  bath  should  now  be  carefully  re- 
moved, a  wire  gauze  substituted  and  the  heat  continued  until 
the  contents  of  the  retort  are  melted.  The  retort  is  now  re- 
moved from  the  neck  of  the  flask,  the  hand  being  protected  by 
a  towel  or  asbestos  holder.  The  fused  hydrogen  potassium 
sulfate  is  poured  out  into  a  thin  400  cc  porcelain  dish  which 
stands  on  a  hot  sand  bath.  In  order  to  free  the  product  from 
the  last  trace  of  saltpeter,  heat  in  the  porcelain  dish  for  a  short 


14  RED    FUMING   NITRIC   ACID. 

time  to  about  280°  over  a  wire  gauze  and  then  pour  into  an  iron 
mold  or  on  a  flat  surface. 

Time  of  Operation:     2  to  2J  hours. 

Yield:  About  100  grams  nitric  acid,  containing  95  to  97 
per  cent.  HNOy 

The  strength  of  the  nitric  acid  is  best  determined  by  titration. 

Properties  and  Tests :  A  slightly  yellowish  liquid,  fuming 
in  the  air  and  beginning  to  boil  at  86°.  It  becomes  heated  on 
mixing  with  water  (use  care!)  The  product  should  be  free 
from  sulfuric  acid.  If  the  saltpeter  and  the  sulfuric  acid  are 
free  from  chlorin  the  nitric  acid  will  be  also. 


5.    Red  Fuming  Nitric  Acid. 

(By-product:   Potassium  Sulfate,  K2SO±.) 
Raw  Materials  :   Saltpeter,  concentrated  sulfuric  acid. 
Red  fuming  nitric  acid  is  a  solution  of  N03  in  nitric  acid, 
with  a  little  water  (HN03-\-N0.2+%H.20.)     It  is  prepared  by 
the  action  of  one  molecule  of  concentrated  sulfuric  acid  on  two 
molecules  of  saltpeter.     At  first  by  the  moderate  heating  of  the 
mixture  nitric  acid  is  formed,  together  with  hydrogen  potassium 
sulfate,  even  though  there  is  an  excess  of  saltpeter  present: 


At  higher  temperature  the  hydrogen  potassium  sulfate  reacts 
with  the  unchanged  saltpeter.  The  nitric  acid  which  is  formed 
is  unstable  at  this  temperature  and  decomposes  (at  256°)  into 
N02,  0, 

(2) 
(3) 

The  NO^  dissolves  in  the  nitric  acid  which  was  produced  in 
the  first  stage  of  the  operation. 


RED    FUMING   NITRIC    ACID.  15 

Exercise:    To  prepare  100  grams  of  red  fuming  nitric  acid. 
Apparatus  :  The  same  as  in  Preparation  4. 

Operation  :  At  first  as  in  Preparation  4.  When  the  con- 
tents of  the  retort  have  become  completely  liquid,  and  the  nitric 
acid  has  ceased  to  drop  in  the  flask,  the  first  stage  of  the  decompo- 
sition is  nearly  completed.  The  sand  bath  is  now  replaced  by 
a  wire  gauze,  and  the  heating  continued  carefully.  Soon  the 
contents  of  the  retort  begin  to  froth,  but  this  soon  ceases,  and 
by  careful  regulation  of  the  flame,  it  is  possible  to  avoid  any 
frothing  over  of  the  contents.  The  fumes  which  fill  the  entire 
apparatus  become  darker  and  at  last  blackish  brown.  If  the 
contents  of  the  retort  solidify,  the  heat  must  be  increased,  but 
not  so  much  that  any  large  quantity  of  brown  fumes  escapes 
between  the  necks  of  flask  and  retort. 

Time  of  Operation  :  About  three  hours. 

After  the  apparatus  is  quite  cold,  pour  the  distillate  into  a 
glass-stoppered  and  weighed  bottle. 

The  amount  of  red  fuming  acid  obtained  should  be  90  to  95 
grams. 

Test  :  The  product  should  be  free  from  sulfuric  acid. 


By-product :    Crystallized  Potassium  Sulfate, 

The  potassium  sulfate  remaining  in  the  retort  is  dissolved  in 
the  amount  of  water  required  for  its  solution  at  100°,  and  the 
boiling,  clear  solution  poured  into  a  wide  porcelain  dish.  On 
cooling,  60  to  70  grams  of  potassium  sulfate  should  crystallize 
out ;  by  evaporating  the  mother  liquor  an  additional  40  to  50 
grams  of  crystals  is  easily  obtained. 

Properties  :  Rhombic  crystals,  anhydrous.  Soluble  in  10 
parts  of  water  at  15°  ;  4  parts  at  100°  ;  melting  point  1078° 
(Victor  Meyer. ) 


16  SODA    AND    ALUMINA    FROM    CRYOLITE. 

6.    Soda  and  Alumina  from  Cryolite. 

(By-product:     Calcium  Fluorid.} 

Raw  Material  :  Finely  powdered  cryolite,  calcined  marble, 
carbon  dioxid. 

Calcium  hydroxid  decomposes  cryolite  at  the  boiling  point  of 
water,  calcium  fluorid  and  sodium  aluminate  being  formed  : 


(1  )  AIFV  3NaF+3Ca  0=Al(  ONa 

If  carbon  dioxid  is  led  into  a  solution  of  sodium  aluminate, 
aluminum  hydroxid  and  sodium  carbonate  are  formed: 

(2)      2  Al(  ONa\+3COt+8Ht  0=2  Al(  OH)9+8Nat  CO,. 

Exercise  :  Convert  100  grams  of  cryolite  into  alumina  and 
soda. 

Operation  :  Burnt  marble1  (about  5  per  cent,  more  than  is 
called  for  by  equation  (1)  )  is  slaked  with  the  requisite  amount 
of  water  in  a  porcelain  dish  holding  about  a  liter,  and  then 
stirred  with  500  grams  of  water,  forming  milk  of  lime.  The 
cryolite,  ground  to  the  finest  possible  powder,  is  added  to  the 
milk  of  lime,  and  the  mixture  heated  over  a  wire  gauze  with 
constant  stirring  to  boiling.  The  boiling  is  continued  for  about 
an  hour,  water  being  added  from  time  to  time  to  replace  that 
lost  by  evaporation.  The  contents  of  the  dish  thicken  more  or 
less,  but  by  constant  stirring  spattering  can  be  avoided. 

The  progress  of  the  decomposition  may  be  best  followed  by 
a  microscope.  When  the  reaction  is  complete,  the  regular, 
sharp-edged  fragments  of  cryolite  are  no  longer  recognizable. 
The  mixture  is  then  diluted  with  about  500  cc  of  hot  water  and 
immediately  filtered.  For  this  purpose  a  linen  cloth  is  used, 


1  The  lime  should  be  as  free  as  possible  from  iron,  and  hence  burnt 
marble  is  the  best  form  to  use. 


SODA  AND  ALUMINA  FROM  CRYOLITE.          17 

stretched  across  a  wooden  filter  frame1  which  rests  upon  a  porce- 
lain dish  (see  Fig.  4. ) 

The  residue  left  on  the 
linen  cloth  is  washed  re- 
peatedly with  warm  water, 
each  time  being  well 
stirred  up.  In  this  way 
the  residue  can  be  washed 
Fig.  4.  Tenaculum  and  Strainer.  to  faint  alkaline  reaction 

by  the  use  of  from  1^  to  2  liters  of  water.  When  the  washing 
is  ended  the  cloth  is  removed  from  the  frame  and  wrung  out 
with  the  hands. 

The  residue  consists  chiefly  of  calcium  fluorid,  with  the  excess 
of  added  lime  (and  calcium  carbonate)  and  is  dried  and  pre- 
served for  Preparation  16. 

The  cloudy  percolate  is  passed  through  a  paper  filter.  Into 
the  clear  solution  carbon  dioxid  is  led  by  a  wide  glass  tube 
until  the  alumina  is  completely  precipitated. 

The  alumina,  like  the  calcium  fluorid,  is  best  filtered  on  linen 
cloth,  washed  and  then  dried.  The  clear  filtrate2  is  evaporated 
to  about  200  grams,  when  on  standing  120  to  150  grams  of 
sodium  carbonate  should  crystallize  out. 

The  amount  of  alumina  obtained  should  approach  95  per  cent, 
of  the  theoretical. 


1  This  form  of  filter  support  (known  as  a  tenaculum),  which  has  been 
in  use  for  centuries,  is  a  square  frame  of  wood.     The  points  of  the  nails 
which  hold  the  corners  together  project  far  enough  out  of  the  wood  for  the 
linen  to  be  hooked  on  to  them.      The  portions  beyond  the  corners  serve  to 
support  the  frame  on  the  rim  of  a  porcelain  dish.     The  liquid  which  is  in. 
this  manner  separated  from  the  solid  material  is  known  as  the  percolate; 
the  apparatus  is  called  a  percolator,  and  the  operation  percolation.    The 
percolate  is  generally  cloudy  and   must  be  clarified  by  filtration  through 
filter  paper. 

2  If  this  filtrate  has  come  in  contact  with  the  wood  of  the  tenaculum 
it  may  have  a  yellowish  tint;  it  can  readily  be  decolorized  by  boiling  with 
animal  charcoal. 


18  ALUM. 

Properties  and  Tests  of  the  Soda:  (Na2COz)10ag.)  Mono- 
clinic  crystals,  which  effloresce  in  the  air,  melt  at  34°,  and  by 
continued  heat  lose  all  their  water  of  crystallization  (dried  or 
calcined  soda.)  The  product  should  be  free  from  lime  and 
alumina.  This  method  of  preparation  avoids  the  usual  im- 
purities of  the  Leblanc  and  ammonia  processes  (chlorin,  sulfuric 
acid  and  ammonia.  ) 

7.    Alum. 


(Intermediate  Product:    Aluminum  Sulfate.] 

Raw  Materials  :  Alumina,  potassium  sulfate,1  concentrated 
sulfuric  acid.  The  equation  for  the  preparation  of  alum  is  as 
follows: 


Exercise:  To  convert  the  aluminum  hydroxid,*  obtained  in 
Preparation  6,  into  alum.  The  amount  of  water  to  be  used  'is 
such  that,  on  cooling,  one-  half  the  product  (alum)  should  crystal- 
lize out. 

Operation  :  Dilute  the  amount  of  concentrated  sulfuric  acid 
required  to  convert  the  alumina  into  aluminum  sulfate  with 
twice  its  weight  of  water.  Dissolve  the  alumina  with  heat,  and 
filter  the  hot  solution  through  a  hot  water  funnel  [the  use  of 
suction  is  advantageous.]  On  cooling,  the  solution  solidifies 
to  a  crystalline  mass,  consisting  of  pearly  flakes  of  aluminum 
sulfate,  Al2(SOJ,,18aq. 

1  Obtained  as  a  by-product  in  Preparation  5. 

2  This  preparation  does  not  have  in  general  the  formula  Al(  OH}~, 
but  a  quantity  of  water  is  present  varying  with  the  method  of  drying. 
This  may  be  expressed   by  the  formula  Al^O^xH^O.      Determine  in  a 
weighed  sample  of  this  aluminum  hydroxid  the  amount  of  alumina,  by 
heating  to  redness  in  a  platinum  crucible. 


SILVER    NITRATE    FROM   COIN   SILVER.  19 

After  the  aluminum  sulfate  has  been  again  brought  into 
solution  by  heat,  it  is  mixed  with  the  solution  of  potassium 
sulfate,  which  contains  the  balance  of  the  water  calculated  as 
necessary. 

Properties  :  Colorless,  transparent  octaedra,  generally  pre- 
senting also  cube  faces;  soluble  in  8  parts  of  water  at  15°. 


8.    Silver  Nitrate  from  Coin  Silver. 
(Intermediate  Product:  Pure  silver.    By-product:  Copper.) 

Raw  fiaterials  :  Coin  silver,  nitric  acid,  hydrochloric  acid, 
soda,  etc. 

Exercise:  Separate  a  25-cent  piece  into  silver,  copper  (and 
gold),  and  convert  the  silver  into  silver  nitrate. 

Operation  :  Cover  the  coin  with  nitric  acid  free  from  chlorin, 
of  specific  gravity  not  above  1.2,  using  for  the  purpose  only  a 
small  excess  of  the  acid  beyond  that  required  by  the  formula: 

(1)  3Ag+4HNOs=3AgN03+2H2  0+NO. 

A  few  little  black  flakes  of  gold  remain  undissolved.  Collect 
these  on  a  small  filter,  and  precipitate  the  blue  solution  with 
hydrochloric  acid.  After 
filtration,  wash  the  silver 
chlorid  until  the  wash- 
water  ceases  to  show  any 
reaction  for  copper.  After 

drying,    mix   the   silver 

_  J     6  Fig.  5.     Eeduction  of  Silver  Chlorid. 

chlorid    thoroughly    with 

double  its  weight  of  calcined  soda,  put  the  mixture  in  a  hollow 
on  a  piece  of  charcoal  A  (Tig.  5),  and  heat  before  the  blast 
lamp1.  In  order  to  prevent  the  dissipation  of  the  heat,  it  is 


1  [The  silver  chlorid  may  be  reduced  more  rapidly  in  a  small  Hes- 
sian crucible  in  a  furnace.] 


20  SILVER   NITRATE    FROM   COIN   SILVER. 

advantageous  to  place  a  second  piece,  B,  of  obliquely  cut  char- 
coal over  A,  as  shown  in  Fig.  5. 


(2) 

The  globules  of  reduced  silver  flow  together  ;  the  sodium 
chlorid  formed  and  the  excess  of  soda  are  absorbed  by  the 
charcoal.  The  fused  silver  absorbs  oxygen,  which  is  given  off 
again  at  the  instant  of  solidification  ("spitting"  of  silver). 
The  upper  surface  of  the  regulus  therefore  appears  rough. 

Yield  :  From  5  grams  of  coin  a  globule  of  silver  weighing 
4.44  grams  can  be  easily  obtained  (in  place  of  the  theoretical 
quantity  4.5  grams). 

For  the  Preparation  of  Silver  Nitrate  the  pure  silver  is 
redissolved  in  nitric  acid.  The  solution  is  evaporated  to  dry- 
ness  in  a  porcelain  dish  on  the  water  bath;  the  residue  is  then 
placed  in  a  small  porcelain  crucible  and  the  last  trace  of  moisture 
driven  off  under  a  hood.  The  silver  nitrate  is  fused  by  careful 
heating  over  a  Bunsen  burner  and  immediately  poured  out  upon 
a  porcelain  plate. 

To  Obtain  the  Copper,  the  filtrate  from  the  silver  chlorid 
precipitate  is  evaporated  to  dry  ness  on  the  water  bath,  the 
residue  dissolved  in  a  small  quantity  of  water,  and  the  copper 
precipitated  as  cuprous  oxid,  by  sodium  hydroxid  and  hydroxyl- 
amin  hydrochlorid  (or  other  suitable  reducing  agent.  ) 

(3)          40u,0  +  2NHtOH=20utO  +  NtO+SHtO. 

The  cuprous  oxid  is  filtered,  thoroughly  washed  and  dried. 
It  is  placed  in  a  bulbed  reduction  tube  of  hard  glass,  connected 
with  a  hydrogen  generator  (see  Fig.  6)  and,  after  the  air  in 
the  tube  has  been  completely  displaced  and  the  escaping  hydro- 
gen lighted  (using  necessary  precaution),  is  heated  with  a  low 
flame.  [A  combustion  furnace  with  a  wide  glass  tube  may  be 
used,  the  cuprous  oxid  being  placed  in  a  porcelain  boat.] 


LIQUID    SULFUR    DIOXID. 


21 


To  Recognize  the  Gold :  Burn  the  filter  paper  which  con- 
tains the  black  residue  left  from  the  solution  of  the  coin  in  nitric 
acid.  Cover  the  ashes  with  a  few  drops  of  aqua  regia  and 


Fig.  6.    Keduction  of  Cuprous  Oxid. 

evaporate  the  solution  to  dryness  on  a  water  bath.  Dissolve  the 
residue  in  a  few  drops  of  dilute  hydrochloric  acid,  filter,  and 
add  to  the  filtrate  a  trace  of  stannous  chlorid  or  ferrous  sulfate 
solution. 


9.    Liquid  Sulfur  Dioxid. 

(By-products:   Ferrous  sulfale,  copper  sulfate.} 

Raw  Materials:     Concentrated  sulfuric  acid,  copper  sulfate, 
iron  filings  free  from  grease,1  rock  salt,  carbon  bisulfid. 


1  To  free  iron  filings  from  grease  they  are  placed  after  drying  in  a 
flask,  covered  with  carbon  bisulfid  and  shaken  thoroughly,  first  stoppering 
the  flask.  After  the  filings  have  settled  the  carbon  bisulfid  is  poured  off 
and  the  process  repeated  once  or  twice.  The  filings  are  then  washed  on  a 
filter  with  carbon  bisulfid  and  allowed  to  dry.  The  carbon  bisulfid  is 
recovered  from  the  united  solutions  by  distilling  on  a  water  bath.  (Com- 
pare with  Fig.  15. )  Use  care  in  working  with  carbon  bisulfid!  (Why  ?) 


22  LIQUID    SULFUR   DIOXID. 

Exercise:  Prepare  100  grams  of  sulfur  dioxid  by  the  action 
of  concentrated  sulfuric  acid  upon  copper,  which  has  been  pre- 
cipitated from  a  solution  of  copper  sulfate  by  the  action  of  metallic 
iron.  Condense  the  gas  to  a  liquid  by  cold. 


A.    Precipitation  of  Copper  from  Copper  Sulfate. 

(By-product:     Ferrous  sulfate.) 

The  precipitation  of  copper  takes   place   according  to   the 
equation : 
(1)  CuSO,  +  Fe  =  FeSO,  +  Ou. 

Operation :  The  quantity  of  copper  needed  for  the  exercise 
is  calculated  from  equation  (2)  (page  24).  The  corresponding 
quantity  of  crystallized  copper  sulfate  (CuSO^Saq)  is  dissolved 
in  a  porcelain  dish  holding  about  1J  liters,  using  sufficient 
water  (previously  boiled)  to  dissolve  the  copper  sulfate  at  80°. 
The  amount  of  iron  filings  should  be  10  per  cent,  more  than 
that  required  by  theory,  because  the  iron  is  generally  not  free 
from  oxid  and  may  contain  other  impurities.  After  the  copper 
sulfate  is  completely  dissolved  and  the  solution  is  heated  to  70° 
or  80°,  carefully  add  the  iron,  a  little  at  a  time,  while  stirring. 
The  contents  of  the  dish  become  heated  to  boiling  by  the 
reaction.  When  the  reaction  has  subsided,  if  the  solution  is 
still  colored  blue,  stir  with  a  wide  strip  of  bright  sheet  iron 
until  the  blade  of  a  pocket  knife  dipped  in  the  solution  ceases 
to  receive  a  coating  of  copper.  Filter  the  hot  solution  through 
a  hot  water  funnel *  into  a  porcelain  dish,  leaving  the  copper  as  far 
as  possible  on  the  bottom  of  the  dish,  and  decant  with  about  100 
cc  of  boiling  water.  When  no  more  liquid  drops  from  the  fun- 
nel, remove  the  filter  paper  and  spirt  the  copper  on  it  back 
into  the  dish  containing  the  mass  of  the  copper,  by  means  of 
a  wash  bottle,  and  clean  the  strip  of  sheet  iron  in  the  same  way. 


[A  Hirsch  funnel  with  suction  is  advantageous.] 


LIQUID    SULFUR   DIOXID.  23 

Time  of  Operation  :    1  to  1J  hours. 

In  order  to  free  the  copper  from  the  iron  mingled  with  it, 
treat  it  with  dilute  sulfuric  acid  on  a  water  bath.     For  filtering 
and  washing  the  copper,  a  sand  filter  is  advan- 
tageously used.     This  is  prepared  by  placing 
a  bulbed  tube1  in  a  funnel  and  covering  it 

?Vy  with  a  layer  of  sea-sand  about  two  centimeters 
deep.  (Fig.  7.)  As  long  as  the  liquid  runs 
through  distinctly  colored  green,  it  is  to  be 
collected  separately,  and  the  washing  then 
continued  until  the  wash -water  no  longer  has 

an  acid  reaction.       Spread  the  copper  on  a 
Fig.  7.  Sand  Filter.  ^^  ^^  ^  ^  ^  in  the  ^      When  ^ 

the  copper  appears  as  a  red-brown  powder,  which  receives  a 
metallic  lustre  by  rubbing  in  an  agate  mortar.  The  amount 
of  copper  obtained  should  correspond  closely  to  theory . 


By-Product  :   Ferrous  Sulfate,  FeSO^  5aq. 

From  the  solution  which  has  been  filtered  from  the  copper, 
there  should  crystallize  about  200  grams  of  ferrous  sulfate. 
Pour  off  the  mother  liquor  and  drain  the  crystals  on  a  Hirsch 
funnel.  The  mother  liquor  and  the  wash-waters,  as  far  as  they 
are  colored  distinctly  green,  are  united  and  evaporated  on  a 
water  bath.  In  this  way  some  200  grams  more  of  ferrous 
sulfate  may  be  recovered. 

Yield  :  90  to  95  per  cent,  of  theoretical. 


B.  Preparation  and  Condensation  of  the  Sulfur  Dioxid. 

(  By-product :  Copper  Sulfate. )  • 

The  principal  reaction  between  copper  and  hot  concentrated 
sulfuric  acid  is: 


1  A  bulb  ia  blown  on  the  end  of  a  small  glass  tube  and  the  other  end 
is  fused  off. 


24 


LIQUID   SULFUR   DIOXID. 


(2) 

The  boiling  point  of  sulfur  dioxid  at  ordinary  pressure  is 
—  8°.  When  cooled  below  this  temperature  ft  is  condensed  to 
a  colorless  liquid.  By  means  of  a  freezing  mixture  of  snow  or 
ice  and  salt,  a  temperature  of  —  21°  is  easily  attained. 

When  gases  are  to  be  condensed  they  should  be  pure  and  dry. 
Acid  gases  are  usually  dried  over  concentrated  sulfuric  acid, 
unless  they  have  a  reducing  action  upon  it.  It  may  happen 
that  in  the  rapid  evolution  of  sulfur  dioxid  some  of  the  sulfuric 
acid  may  be  carried  along  with  it  mechanically;  to  absorb  such 
sulfuric  acid,  the  stream  of  gas  is  passed  over  solid  potassium 
sulfate  : 


Apparatus:  See  Fig.  8.  The  flask  A  and  the  wash  bottle  B  are 
arranged  as  in  Preparation  1  (Fig.  1).  From  the  wash  bottle  the  gases 
pass  through  the  tube  g,  which  is  filled  with  crystals  of  potassium  sulfate. 


Fig.  8.     Preparation  of  Liquid  Sulfur  Dioxid. 

The  gases  then  enter  the  U-shaped  tube  C,  in  which  the  liquid  sulfur 
dioxid  is  condensed.  The  U-tube  stands  in  an  earthen  vessel  D,  filled 
with  the  freezing  mixture,  and  is  connected  with  the  bulbed  tube  h,  which 


LIQUID    SULFUR    DIOXID.  25 

dips  just  below  the  surface  of  water  in  flask  E.     This  water  serves  to 
absorb  any  sulfur  dioxid  which  is  not  condensed  in  the  U-tube. 

The  tube  g  is  of  the  general  form  and  size  of  a  calcium 
chlorid  tube,  and  may  be  filled  with  the  potassium  sulfate 
obtained  as  a  by-product  in  Preparation  5;  the  salt  should  be 
first  freed  from  powder  by  sifting, 

The  branches  of  the  U-tube  C  are  about  25  cm  long  and 
15  to  18  mm  in  diameter;  both  ends  are  drawn  out  and  bent 
at  right  angles. 

The  bulbed  tube  h  rests  by  its  bulb  on  the  neck  of  the 
flask  E.  The  length  of  the  tube  below  the  bulb  is  such  that 
when  100  to  150  cc  of  water  are  in  the  flask,  the  end  dips 
just  below  the  surface  of  the  water.  Fig.  9. 

Fig.  9  shows  the  tube  prepared  for  sealing  up  the  sulfur 
dioxid,  standing  in  a  glass  cylinder  filled  with  freezing  mixture.      The 
tube  is  made  from  thick  walled  tubing,  and  is  about  40  cm  long.      One 
end  is  sealed  off  and  the  other  drawn  out  into  a  thick  walled  capillary 
tube. 

Operation  :  After  the  apparatus  has  been  tested  in  all  its 
parts  and  found  to  be  air-tight,  the  copper  is  placed  in  the 
flask;  sufficient  concentrated  sulfuric  acid  is  placed  in  the  wash 
bottle  for  the  entrance  tube  to  dip  about  2  cm  below  the  surface; 
the  earthen  vessel  around  the  U-tube  is  filled  with  alternate 
layers  of  snow  or  pounded  ice  (3  parts)  and  rock  salt1  (1  part). 
700  grams  of  concentrated  sulfuric  acid2  are  then  poured  upon 
the  copper.  The  flask  is  shaken  and  the  lamp  lighted  under 
the  sand  bath.  As  soon  as  the  evolution  of  bubbles  in  the  flask 
shows  that  the  copper  has  begun  to  act  upon  the  sulfuric  acid, 
the  flame  is  extinguished.  The  heat  of  reaction  is  generally 
sufficient  to  keep  up  a  rapid  evolution  of  gas.  The  air  expelled 
by  the  stream  of  gas  escapes  by  the  bulbed  tube.  The  sulfur 


1  The  quantity  depends  upon  the  size  of  the  vessel ;    for  a  1  liter  ves- 
sel 700  g  ice  and  230  g  salt  are  sufficient.      If  the  vessel   holds  3  or  4 
liters  once  filling  with  the  freezing  mixture  will  suffice  for  the  whole  oper- 
ation. 

2  This  is  more  than  double  the  theoretical  quantity ;   why  is  an  excess 
of  sulfuric  acid  necessary  ? 


26  LIQUID    SULFUR    DIOXID. 

dioxid  carried  along  by  this  air  is  absorbed  by  the  water  in  the 
flask.     After  a  short  time  this  escape  of  air  bubbles  ceases. 

The  flame  under  the  sand  bath  should  not  be  again  lighted 
until  the  rapidity  with  which  the  gas  bubbles  through  the  wash 
bottle  begins  to  lessen.  It  should  then  be  so  regulated  that 
there  should  be  a  fairly  rapid  evolution  of  gas,  but  not  too  much 
frothing  of  the  contents  of  the  flask.  As  the  liquified  sulfur 
dioxid  collects  in  the  U-tube  the  pressure  in  the  apparatus 
rises.  It  is  well  to  have  about  20  grams  of  mercury  at  hand,  to 
pour  into  the  safety  funnel,  when  the  height  of  the  column  of 
liquid  in  it  is  no  longer  sufficient  to  overcome  the  increased 
pressure. 

Toward  the  end  of  the  operation  the  upper  part  of  the  flask 
becomes  covered  with  a  yellowish  film  of  sulfur,1  which  grad- 
ually increases.  Some  sulfur  may  also  be  carried  over  into 
the  wash  bottle,  though  generally  without  any  danger  of  stopping 
up  the  tubes.  When  the  connection  tubes  and  the  contents  of 
the  wash  bottle  have  become  hot,  the  operation  is  completed. 

Time  of  Operation :     2^  to  3  hours. 

The  tube  prepared  for  the  sulfur  dioxid  is  weighed  and  then 
surrounded  in  a  high  glass  cylinder  with  a  freezing  mixture. 
The  liquid  in  the  U-tube  is  poured  in  with  great  care  (under  a 
draught)  and  the  tube  closed  by  fusing  before  a  blast  lamp  or  a 
blow  pipe  the  part  which  has  been  drawn  out. 

The  yield  is  usually  not  more  than  50  per  cent,  of  the 
theoretical;  it  is  influenced  by  the  incomplete  condensation  of 
the  first  portion  of  the  gas  coming  over  with  the  air,  by 
secondary  reactions,  and  lastly  by  decided  loss  in  filling  the 
tube. 

Properties:     Colorless  liquid,  boiling  at  — 8°  (Pierre)  and 

1  Hydrogen  sulfid  is  formed,  which  reacts  with  the  sulfur  dioxid  : 


IRON   AMMONIUM   ALUM.  27 

solidifying  at  — 76°  (Faraday.)     Its  tension  in  closed  vessels  is 
at  0°,  1.7  atmospheres;  at  10°,  2.3  atm. ;  at  20°,  3.3  atm.,  etc. 


By-product:      Copper  sulfate,  CuS0^5aq. 

Add  with  care  about  750  cc1  of  water  to  the  contents  of  the 
flask. 

Boil  the  mixture  and  filter  the  blue  solution  from  the  in- 
soluble black  substance  into  a  porcelain  dish.  On  cooling,  the 
greater  part  (about  300  grams)  of  the  copper  sulfate  crystallizes 
out.  Wash  the  residue  remaining  on  the  filter  paper  with  hot 
water  until  the  wash  water  has  no  longer  an  acid  reaction.  As 
long  as  the  filtrate  is  distinctly  blue,  collect  it  separately.  Add 
the  blue  filtrates  to  the  mother  liquor  from  the  crystals,  and 
evaporate  on  the  water  bath  to  crystallization.  An  additional 
50  to  60  grams  of  crystals  may  be  obtained  in  this  way. 

Yield:  Nearly  90  per  cent,  of  the  copper  sulfate  originally 
used.  About  10  grams  or  less  of  black  substance  is  left  upon 
the  filter  paper.  Determine  its  composition  by  qualitative  ex- 
amination and  account  for  its  formation. 

Properties:     Blue,  triclinic  crystals. 
The  product  should  not  contain  iron. 


10.    Iron  Ammonium  Alum. 


Raw   Materials:     Ferrous   sulfate,  ammonia,  concentrated 
sulfuric  acid,  nitric  acid. 


1  This  is  much  more  water  than  corresponds  to  the  solubility  of  the 
blue  vitriol  in  the  water;  its  solubility  is  decidedly  lessened  by  the  pres- 
ence of  the  excess  of  sulfuric  acid. 


28  IRON   AMMONIUM   ALUM. 

The  preparation  of  iron  ammonium  alum  is  according  to  the 
equation  : 


2NO. 

Exercise  :  Prepare  500  grams  of  iron  ammonium  alum  in 
such  a  manner  that  at  the  end  of  the  reaction  two-thirds  of  the 
product  shall  crystallize  out,  on  cooling,  without  further  evapora- 
tion of  the  solution. 

Operation:  The  ferrous  sulfate  to  be  used  is  that  which 
was  obtained  as  a  by-product  in  Preparation  9  ;  the  nitric  acid 
should  have  sp.  gr.  1.30  to  1.40;  the  ammonia  sp.  gr.  0.90  to 
0.95;  the  sulfuric  acid  should  be  concentrated.  Calculate  the 
required  quantity  of  each  ingredient,  paying  particular  attention 
to  the  water  present  in  each;  from  the  solubility  of  the  alum  is 
calculated  the  further  amount  of  water  which  must  be  used. 
Add  to  the  ferrous  sulfate  in  a  2-liter  flask  the  calculated 
amount  of  water  and  then  (with  great  care!)  the  concentrated 
sulfuric  acid.  Place  the  flask  over  a  water  bath  under  a  good 
draught,  hang  in  the  mouth  of  the  flask  a  funnel  and  add  the 
nitric  acid  in  small  portions.  Immediately  upon  the  addition 
of  the  first  drops  the  liquid  becomes  dark  brown  and  soon  the 
flask  is  filled  with  brown-red  fumes.  Upon  the  addition  of  the 
last  portions  of  the  nitric  acid  a  violent  evolution  of  gas  may 
take  place  ;  hence,  much  care  must  be  used.  Heat  the  con- 
tents of  the  flask  over  a  wire  gauze,  remove  the  funnel  from 
the  neck  of  the  flask  and  boil  until  the  colored  fumes  cease  to 
be  evolved.  Withdraw  a  few  drops  of  the  liquid  with  a  pipette 
and  after  dilution  test  for  ferrous  iron.  If  the  oxidation  is 
complete,  pour  the  contents  of  the  flask  into  a  porcelain  dish 
and  add  the  ammonia  with  constant  stirring.  In  this  operation 
no  permanent  precipitate  should  be  formed.  The  clear  liquid 
should  have  a  greenish  brown  color. 


POTASSIUM    NITRITE.  29 

Time  of  Operation :     1  to  1^  hours. 

Yield:  On  cooling  the  liquid,  from  200  to  250  grams  of 
iron  ammonium  alum  should  be  obtained,  generally  in  beautiful 
crystals.  By  concentration  of  the  mother  liquor  the  yield  may 
readily  be  increased  by  some  100  grams. 

Properties :  Pale  violet,  transparent  octaedra,  soluble  in  3 
parts  of  water  at  15°. 


ii.     Potassium  Nitrite. 
(By-product:  Lead  Oxid. ) 

Raw  Materials  :   Saltpetre,  lead. 

In  fused  condition  at  high  temperature  saltpetre  and  lead 
react  upon  each  other  according  to  the  following  equation  : 

KNO,+Pb=KNO,+Pb  0. 

This  reaction  goes  on  spontaneously  at  a  temperature  which 
is  somewhat  above  the  melting  point  of  lead  (334°)  and  salt- 
peter (340°).  It  is  impossible,  without  special  forms  of  appa- 
ratus, to  regulate  temperatures  of  this  intensity  within  narrow 
limits,  and  this  is  especially  true  when  the  temperature  is 
modified  by  the  heat  of  reaction.  When  saltpeter  is  heated 
by  itself  to  a  temperature  considerably  above  its  melting  point  it 
is  decomposed  partially  into  oxygen  and  potassium  nitrite,  while 
at  a  still  higher  temperature  the  nitrite  is  in  turn  decomposed 
into  oxygen,  nitrogen  and  potassium  oxid.  In  the  preparation 
of  potassium  nitrite  these  secondary  reactions  cannot  be  wholly 
avoided.  Furthermore,  a  part  of  the  saltpeter  can  easily  fail 
to  come  into  contact  with  the  lead.  For  this  reason  it  is  best 
to  use  somewhat  less  lead  than  is  demanded  by  the  equation. 

Exercise:  Convert  250  grams  of  saltpeter  into  potassium 
nitrite  as  above  described.1 

1  For  250  grams  saltpeter  400  grams  lead  are  sufficient. 


30 


POTASSIUM    NITRITE. 


Apparatus  :  To  reach  the  temperature  demanded  for  the  operation,  a 
large  gas  furnace  (after  Rossler,  Miincke,  Perrot,  etc.)  or  an  arrangement 
for  charcoal  heating  is  required.1  The  heating  of  the  saltpeter  and  lead 
is  best  carried  out  in  a  flat  round  iron  pan,  about  30  cm  in  diameter  with 
a  long  handle.  For  stirring,  a  long  iron  spatula  with  a  wooden  [or 
asbestos]  handle  is  necessary. 

Operation  :  After  the  saltpeter  has  been  melted  in  the  iron 
pan  over  a  gas  flame  or  charcoal  fire,  add  50  to  60  grams  of 
lead  and  stir  together  with  the  iron  spatula  till  all  the  lead  is 
oxidized.  The  heat  must  be  so  regulated  that  only  a  very 
slight  evolution  of  gas  takes  place;  it  is  impossible  to  avoid  all 
decomposition.  The  remainder  of  the  lead  is  to  be  added  to 
the  melted  mass  in  portions  of  about  50  grams,  each  portion 

being  stirred  thoroughly  before  the 
next  is  added.  After  each  stir- 
ring no  large  globules  of  fused 
lead  should  be  visible.  As  the 
quantity  of  lead  oxid  increases 
the  melt  thickens.  Toward  the 
end  of  the  operation  the  heat  is 
increased  very  carefully,  but  the 
bottom  of  the  pan  must  not  become 
more  than  faintly  red  hot.  In  the 
pasty  mass  spots  of  incandescence 
are  often  visible.  When  all  the 
lead  (400  grams)  has  been  added 
and  fully  oxidized,  take  the  pan 
from  the  fire,  continuing  the  stir- 
ring until  the  melt  solidifies  to  a  lumpy  mass  which  may  be 
readily  removed  from  the  pan. 

Time  of  Operation  :   About  1  hour. 

After  the  melt  is  cold,  it  is  placed  in  a  strong  stand  glass 

1  For  this  purpose  a  portable  furnace  of  strong  sheet  iron  lined  with 
firebrick  is  sufficent.  The  dimensions  may  be  0.4  meter  high  and  0.3 
meter  square,  as  is  shown  in  Fig.  10. 


Fig.    10.      Portable  Furnace 
for  Charcoal   Firing. 


POTASSIUM   NITRITE.  31 

and  covered  with  about  250  grams  of  water,  which  has  already 
been  used  to  clean  the  pan.  When  the  lumps  have  become 
disintegrated,  pour  the  solution  from  the  heavy  sediment  into  a 
beaker  glass,  and  stir  100  cc  of  warm  water  into  the  sediment 
and  decant.  Kepeat  this  ten  or  twelve  times,  each  time  using 
about  100  cc  of  hot  water.  Then  pour  the  litharge  stirred  up 
with  water  on  to  a  filter,  leaving  the  unchanged  lead  in  the 
glass.  Wash  the  litharge  on  the  filter. 

The  united  extracts  give  about  1.5  liters  of  'solution  and  have 
an  alkaline  reaction.  After  neutralization  with  dilute  sulfuric 
acid  added  drop  by  drop,  filter,  and  evaporate  the  clear  solution 
on  the  water  bath  till  its  weight  is  about  300  grams.  On  cool- 
ing, the  greater  part  of  the  undecomposed  saltpeter  (50  to  75 
grams)  crystallizes  out,  while  the  potassium  nitrite  remains  in 
solution.  The  solution,  separated  from  the  crystals,  is  now 
evaporated,  with  constant  stirring,1  to  dryness  on  a  sand  bath 
in  a  thin  walled  porcelain  dish.  It  is  then  fused  over  a  free 
flame  and  poured  in  a  mould  or  on  a  porcelain  plate.  The 
product  should  be  placed  in  a  tightly  stoppered  bottle  just  as 
soon  as  it  is  sufficiently  cool  to  handle. 

Yield  :  1.  Potassium  nitrite:  95  to  97  per  cent,  of  the  theo- 
retical amount  from  the  saltpeter  used  (the  amount  taken,  less 
that  recovered)  ;  2.  Leadoxid:  nearly  the  theoretical  amount. 

Test  of  the  Potassium  Nitrite  :  The  product  always  con- 
tains some  saltpeter,2  but  should  be  free  from  lead.  The 
determination  of  the  percentage  of  potassium  nitrite  in  the  pro- 
duct is  carried  out  by  titrating  with  potassium  permanganate 
in  a  sufficiently  dilute  solution: 


0. 


1  Great  care  must  be  taken  to  shield  the  eyes  from  the  spattering  of 
the  hot  mass. 

2  Nitric  acid  is  to  be  tested  for  after  the  nitrous  acid  has  been  decom- 
posed by  urea  (see  page  51.) 


32  PHOSPHORIC   ACID. 

12.     Phosphoric  Acid. 

(  Orthophosphoric  acid,  .Z73P04.) 

Raw   Materials  :    Red   ( '  amorphous ' )   phosphorus,   nitric 
acid,  sp.  gr.  1.21  to  1.2.4;  (alcohol  and  ether.) 

Both  yellow  and  red  phosphorus  are  oxidized  by  the  action 
of  nitric  acid  to  phosphoric  acid.  If  the  nitric  acid  is  stronger 
than  that  which  corresponds  to  sp.  gr.  1.24  the  reaction  goes 
on  spontaneously  with  great  violence.  Yellow  phosphorus  is 
apt  by  this  action  to  be  spattered  out  of  the  liquid  and  ignited. 
If  the  nitric  acid  is  weaker,  the  oxidation  proceeds  very  slowly. 
The  red  phosphorus  is  much  more  quickly  and  safely  converted 
into  phosphoric  acid,  since  by  not  melting  it  offers  a  much  larger 
surface  to  the  action  of  the  acid,  and  it  does  not  ignite  at  the 
boiling  point  of  the  nitric  acid.  The  reaction  takes  place 
approximately  according  to  the  following  equation : 
(1)  3P+5HNOs+2H^O  =  3HfOi+5NO. 

Exercise  :     Convert  31  grams  of  red  phosphorus  into  phos- 
phoric add. 

The  red  phosphorus  is  first  to  be  washed1  with  water.  For  this  pur- 
pose stir  about  60  grams  of  red  phosphorus2  with  water  in  a  beaker 
glass.  After  the  phosphorus  has  settled,  decant  through  a  filter,  and  repeat 
this  until  the  wash  water  has  but  a  very  weakly  acid  reaction;  then  wash 
the  phosphorus  on  to  the  filter.  After  very  thorough  washing  with  water, 
rinse  off  with  alcohol  and  then  with  ether,  in  order  to  be  able  to  dry  the 
phosphorus  more  quickly.  Spread  the  filter  with  the  phosphorus  on 
absorbent  paper  to  dry. 

Operation  :    Place  the  quantity8  of  nitric  acid  (sp.  gr.  1.21 

1  Commercial  red  phosphorus  contains  as  impurities  phosphoric  acid, 
phosphorous  acid,  arsenic,  tin,  iron,  etc. 

2  60  grams  in  order  to  have  sufficient  purified  phosphorus  for  Prep- 
aration 23. 

3  Actually,  less  than  the  theoretical  amount  of  nitric  acid  is  used, 
since  in  the  reaction  some  N  is  formed  as  well  as  NO,  and  nitric  acid  is 
partly  regenerated  (in  what  way?) 


PHOSPHORIC    ACID.  33 

to  1.24)  required  by  equation  (1)  in  a  round-bottomed  2  liter 
flask,  add  at  first  10  grams  phosphorus  and  set  the  flask  on  a 
straw  ring  under  a  hood. 

If  no  marked  heating  takes  place  spontaneously  within  ten 
minutes,  warm  the  flask  upon  a  water  bath  which  has  been 
already  prepared  and  heated,  but  continue  the  warming  only 
till  an  evolution  of  gas  begins  and  colored  gas  is  visible  in  the 
flask.  Then  take  the  flask  immediately  from  the  water  bath, 
place  it  again  upon  the  straw  ring,  and  hang  a  large  funnel  in 
the  neck.  The  reaction  becomes  very  quickly  more  active  and 
the  liquid  begins  to  froth  and  boil  ;  brown  fumes  escape  from 
the  flask,  a  part  of  which  condense  on  the  funnel  and  fall  back 
into  the  'flask.  When  the  evolution  of  gas  has  ceased  and  the 
reddish  brown  color  of  the  fumes  in  the  flask  has  changed  over 
into  yellowish-brown,  remove  the  funnel  and  add  5  grams  more 
of  phosphorus.  The  reaction  begins  anew  and  goes  on  as  before. 
The  remainder  of  the  phosphorus  is  added  in  portions  of  about  5 
grams,  the  reaction  being  allowed  to  subside  each  time  before 
more  phosphorus  is  added. 

Time  of  Operation:     li  to  2  hours. 

The  contents  of  the  flask  consist  of  phosphoric  acid,  phos- 
phorous acid,  the  excess  of  nitric  acid,  and  are  generally  colored 
by  the  brownish-black  arsenic  which  has  remained  undissolved. 
This  liquid  after  cooling  is  poured  into  a  retort  holding  about  f 
liter,  and  most  of  the  excess  of  nitric  acid  is  distilled  off  on  a 
sand  bath  (see  Fig.  3. )  Toward  the  end  of  the  distillation  a 
rather  violent  reaction  again  takes  place,  which  is  caused  by  the 
oxidation  of  the  phosphorous  acid.  When  this  occurs,  dark 
brown  fumes  are  given  off  and  in  part  escape  from  the  neck  of 
the  receiver.  The  reaction  ceases  suddenly  and  the  distillation 
is  then  stopped.1 

1  The  distillate  consists  of  about  150  to  180  grams  of  10  to  12  per 
cent.  HNOZ. 


34  PHOSPHORIC    ACID. 

The  residue  in  the  retort  is  poured  into  a  flask  and  diluted 
with  water  to  about  a  liter.  Hydrogen  sulfid  is  then  led  into 
the  warm  liquid  for  two  or  three  hours,  to  precipitate  the 
arsenic,  which  has  been  dissolved,  and  the  whole  is  allowed  to 
settle  over  night.  The  next  morning  if  the  contents  of  the  flask 
smell  strongly  of  hydrogen  sulfid,  the  yellow,  flaky  precipitate1  is 
filtered  off ;  otherwise  hydrogen  sulfid  is  again  led  in  until  all 
the  arsenic  is  precipitated. 

The  clear  filtrate  is  now  evaporated  on  a  water  bath  in  a 
porcelain  dish  until  its  volume  ceases  to  diminish.  It  is  then 
transferred  to  a  smaller,  thin-walled  dish,  and  heated  first  on  a 
sand  bath  and  then  over  wire  gauze  until  a  thermometer  in  the 
liquid  stands  at  180°.  Before  heating  on  the  sand  bath  remove 
a  small  sample  from  the  dish  and  test  for  phosphorous  acid.  If 
silver  nitrate  is  reduced  by  boiling  with  the  diluted  sample,  add 
10  to  20  grams  of  nitric  acid  of  sp.  gr.  1.21  to  the  contents  of 
the  porcelain  dish.  The  finished  product  is  to  be  immediately 
placed  in  a  previously  warmed,  glass-stoppered  bottle. 

Yield :  90  to  95  grams  of  phosphoric  acid,  in  place  of  ?  grams. 

Properties  and  Tests:  Colorless,  syrupy  mass,  which  solidi- 
fies suddenly  with  evolution  of  heat  on  adding  a  crystal  of 
phosphoric  acid.  Heated  above  180°  it  is  gradually  changed 
with  loss  of  water  into  pyrophosphoric  acid.  Slight  heat  only 
is  developed  on  mixing  the  acid  with  water.  In  aqueous  solution 
magnesia  mixture  gives  a  white,  crystalline  precipitate;  ammo- 
nium molybdate  gives  a  yellow  precipitate,  insoluble  in  nitric 
acid,  but  soluble  in  ammonia  ;  silver  nitrate  with  a  little  am- 
monia gives  a  lemon-yellow  precipitate  (distinction  from  pyro- 
phosphoric acid);  it  does  not  coagulate  albumen  (distinction 
from  metaphosphoric  acid. )  The  product  should  be  free  from 
phosphorous  acid  and  from  arsenic  compounds. 

1  A  qualitative  examination  of  the  precipitate,  which  often  amounts  to 
more  than  a  gram,  will  show  whether  it  consists  of  As.2Sz  only,  or  also 
contains  SnS2. 


DISODIUM    PHOSPHATE.  35 

13.   A.  Disodium  phosphate,    B.   Sodium  ammo- 
nium  phosphate,       C.    Pyrophosphoric 
acid,     D.    Metaphosphoric  acid. 

Raw   Materials  :     Orthophosphoric  acid,  crystallized  soda, 
ammonium  chlorid,  sugar  of  lead,  hydrogen  sulfid.      (Alcohol. ) 


A.    Disodium  Phosphate. 

Exercise:  Convert  75  grams  of  the  phosphoric  acid  obtained 
in  Preparation  12  into  crystallized  disodium phosphate  accord- 
ing to  the  equation : 

( 1 )   HZPO,  +  Na2  C03,  lOaq  +  H,  0  =  HNafO^  12aq+C02. 

The  quantities  to  be  used  are  such  that  on  cooling  the  solution 
after  reaction,  two-thirds  of  the  product  shall  crystallize  out. 

Operation:  Dilute  the  phosphoric  acid  with  the  required 
amount  of  water,  account  being  taken  of  the  water  of  crystalli- 
zation in  the  soda.  Warm  the  solution  and  slowly  add  the 
calculated  quantity  of  soda  crystals.  The  solution  should  be 
only  slightly  alkaline1  in  reaction.  Let  the  solution  stand  over 
night  and  then  drain  the  crystals  on  a  Hirsch  filter.  After  the 
mother  liquor  has  drained  away  as  far  as  possible,  dry  the 
crystals  by  pressure  between  filter  paper. 

Yield:     About  130  grams  of  disodium  phosphate. 

Properties:  Monoclinic  prisms,  which  effloresce  rapidly  in 
the  air;  the  aqueous  solution  has  an  alkaline  reaction.  On 
heating,  sodium  pyrophosphate  is  formed.2 

1  /.  e. ,  a  sample  of  it  should  become  acid  on  the  addition  of  very  few 
drops  of  hydrochloric  acid. 

2  For  solubilities  see  pages  72,  73. 


36  SODIUM   AMMONIUM    PHOSPHATE. 

B.     Sodium  Ammonium  Phosphate. 

HNaNH±  P04,  4aq.     (  Microcosmic  salt.  ) 

Exercise:  Convert  150  grams  of  disodium  phosphate  into 
sodium  ammonium  phosphate  according  to  the  equation: 

(2)  HNa2PO,  +  NH±  Cl  =  HNaNHfO,  -f  Na  Cl. 

Operation:  Dissolve  the  disodium  phosphate  and  also  the 
equivalent  amount  of  ammonium  chlorid  in  the  smallest  possible 
quantity  of  hot  water  and  mix  the  solutions.  The  product 
which  crystallizes  out  contains  sodium  chlorid  and  must  be 
purified  by  recrystallization. 

Properties  :  Sodium  ammonium  phosphate,  also  called  'phos- 
phorsalt',  'salt  of  phosphorus,'  and  'microcosmic  salt,'  crystal- 
lizes in  monoclinic  prisms,  which  effloresce  gradually  in  the  air 
and  lose  their  ammonia.  On  heating,  sodium  metaphosphate 
is  formed. 

C.     Pyrophosphoric  Acid. 

BAO+ 

Exercise  :  Prepare  a  10  per  cent,  aqueous  solution  of  pyro- 
phosphoric  acid. 

Operation  :  Heat  20  to  30  grams  of  disodium  phosphate, 
.with  constant  stirring,  in  a  porcelain  dish  over  a  wire  gauze, 
until  the  salt  has  again  become  solid.  Fill  a  platinum  crucible 
half  full  of  the  dry  salt  and  heat  it  first  over  a  Bunsen  burner 
and  then  over  the  blast  lamp.  Care  must  be  taken  that  the 
point  of  the  flame  of  the  blast  lamp,  and  not  the  reducing  por- 
tion, comes  in  contact  with  the  crucible.1  The  heating  is  to  be 
continued  until  no  more  gas  bubbles  are  given  off  from  the 
fused  mass. 

(3)  2HNa2PO=Na,P.z  0,+H2  0. 


1  Otherwise  the  platinum  easily  becomes  brittle. 


META  PHOSPHORIC    ACID.  37 

After  cooling,  dissolve  the  contents  of  the  crucible  in  ten  times 
their  weight  of  water,  and  add  a  concentrated  solution  of  lead 
acetate,1  corresponding  to  the  equation  : 

(4)  Na^P20,+2Pb(  C2H,02\=Pb,Pl201-\-4^rO'C2H302. 
Filter  off  the  precipitated   lead  salt,  wash  first  with  water 

and  then  with  alchohol,2  until  no  more  lead  can  be  detected  in 
the  filtrate.  After  it  is  dry,  powder  the  lead  pyrophosphate 
and  cover  it  with  sufficient  water  to  yield  a  10  per  cent,  solution 
of  pyrophosphoric  acid.  Hydrogen  sulfid  is  then  led  into  the 
solution  until  the  white  lead  salt  is  completely  converted  into 
black  lead  sulfid: 

(5)  Pb2P2  0,+2H2S=2PbS  +  JET4P2  0r 

The  solution  of  pyrophosphoric  acid  after  filtration  is  placed 
in  a  dessicator  over  lime  until  the  odor  of  hydrogen  sulfid  has 
completely  disappeared. 

Properties  :  The  solution  cannot  be  concentrated  by  evapo- 
ration, since  by  this  the  pyrophosphoric  acid  changes  over  into 
orthophosphoric  acid.  Silver  nitrate  gives  a  white  pulverulent 
precipitate  (distinction  from  orthophosphoric  acid);  albumen 
is  not  coagulated  (distinction  from  metaphosphoric  acid.) 

D.     Metaphosphoric   Acid. 

Exercise  :  Prepare  a  10  per  cent,  aqueous  solution  of  meta- 
phosphoric acid. 

This  preparation  is  made  from  microcosmic  salt  in  the  same 
way  as  pyrophosphoric  acid  from  disodium  phosphate.  The 
equations  are: 

(  1  )  HNaNHfO=NaPOs+NHz+  H,  0, 

(2) 
(3) 


1  1  part  of  water  at  40°  dissolves  ]  part  of  Pb(C2Hs02}2  3  aq. 

2  Lead  acetate  and  sodium  acetate  are  soluble  in  alcohol  ;   lead  pyro- 
phosphate is  insoluble  in  alcohol. 


38  LEAD    PEROXID. 

Properties  :  This  solution  cannot  be  concentrated  by  evapo- 
ration owing  to  the  fact  that  metaphosphoric  acid  is  gradually 
changed  into  pyrophosphoric  acid.  Silver  nitrate  gives  a  white 
gelatinous  precipitate.  The  aqueous  solution  of  metaphosphoric 
acid  coagulates  albumen  solution  (distinction  from  ortho-  and 
pyro-phosphoric  acid. ) 


14.     Lead  Peroxid. 
(Intermediate  Product:  Lead  Acetate.) 

Raw  flaterials  :  Lead  oxid  (litharge),  glacial  acetic  acid, 
soda,  common  salt,  manganese  dioxid,  concentrated  sulfuric 
acid,  dilute  nitric  acid. 

Acetic  acid  converts  litharge  into  lead  acetate  (sugar  of  lead) 
according  to  the  equation  : 

(1)  PbO+2C2HtO=Pb(C2H302\+H20. 

If  the  solution  of  lead  acetate  is  treated  with  soda,  and 
chlorin  led  into  the  mixture,  lead  peroxid  is  formed  : 

(2)  Pb(CtHMt+Na,COt+2Cl+H,0 

=Pb  0,+2Na  Cl+2C,Ht  02+  C02. 

Exercise  :  Convert  100  grams  of  litharge  into  lead  acetate, 
and  from  100  grams  of  this  product  prepare  lead  dioxid. 

Operation  :  a.  Preparation  of  lead  acetate.  Use  100  grams 
of  the  litharge1  obtained  as  a  by-product  in  Preparation  11. 
Cover  the  litharge  in  a  porcelain  dish  with  the  amount  of  33 
per  cent,  acetic  acid2  required  by  equation  (1),  and  heat  to  boil- 
ing. As  soon  as  the  litharge  is  dissolved,  filter  through  a  hot 


1  This  litharge  is  usually  contaminated  with  iron  oxid  and  lead  car- 
bonate.    If  the  latter  is  present  there  will  be  effervescence  on  the  addi- 
tion of  acetic  acid. 

2  One  part  of  glacial  acetic  acid  and  two  parts  water. 


LEAD    PEROXID.  39 

water  funnel.  It  may  be  found  necessary  to  add  somewhat 
more  acetic  acid  to  complete  the  solution.  On  cooling,  the 
solution  solidifies  to  a  crystalline  mass  of  fine  needles.  Drain 
off  the  brown  mother  liquor  (why  brown  ?)  with  a  filter  pump, 
and  dry  the  crystals  between  filter  paper.  The  product,  known 
as  sugar  of  lead,  has  the  composition  Pb  (C2H302)23aq. 
b.  Preparation  of  lead  dioxid.  Dissolve  in  water,  each  by  itself, 
100  grams  of  sugar  of  lead,  and  the  quantity  of  soda  required 
by  equation  (2).  Mix  the  solutions  in  a  liter  flask  and  lead 
chlorin  into  the  mass  through  a  glass  tube  which  reaches  to  the 
bottom  of  the  glass.  Continue  the  current  of  chlorin  until  the 
white  carbonate  is  completely  converted  into  the  brown  peroxid. 

To  prepare  the  chlorin,  place  in  a  flask  an  intimate  mixture 
of  two  parts  finely  powdered  pyrolusite  (MnO^  and  two  parts 
salt,  and  add  a  cooled  mixture  of  six  parts  concentrated  sul- 
furic  acid  with  two  parts  water. 

This  corresponds,  when  the  the  pyrolusite  contains  70  per 
cent.  Mn02,  approximately  to  the  equation  : 

(3)  2NaCl+3H,SO,+MnO, 

=2HNaSO^MnS0^2Cl^2H2  0. 

The  evolution  of  chlorin  begins  in  the  cold,  but  should  be 
assisted  by  gentle  warming  of  the  flask  on  a  sand  bath.  By 
careful  regulation  of  the  temperature  a  steady  stream  of  chlorin 
is  obtained. 

A  wash  bottle  (B  Fig.  1)  with  water  should  be  placed  be- 
tween the  flask  in  which  the  chlorin  is  evolved  and  the  vessel 
in  which  the  lead  peroxid  is  formed.  At  the  beginning  of  the 
reaction  more  or  less  chlorin  escapes  unused,  hence  the  mate- 
rials used  for  the  evolution  of  chlorin  must  be  in  excess  of  the 
theoretical  quantity;  usually  one-third  more  than  is  required  by 
equation  (2)  will  be  sufficient.  After  the  operation,  which  requires 
about  1^  hours,  is  ended  the  contents  of  the  flask  containing 
the  lead  peroxid  are  warmed  on  the  water  bath,  poured  into  a 


40  ANTIMONY    TRICHLORID. 

beaker  glass,  and  the  clear  'supernatant  liquid  decanted.  The 
lead  peroxid  is  then  digested  in  the  beaker  glass  with  dilute 
nitric  acid,  in  order  to  dissolve  out  any  undecomposed  lead 
carbonate  ;  after  repeated  decantations  with  warm  water  it  is 
filtered  and  washed  until  the  wash'water  .ceases  to  show  an  acid 
reaction. 

Yield  :  62  to  65  grams  lead  peroxid,  in  place  of  ?  grams 
required  by  theory. 

Properties  and  Tests  :  Dark  brown  amorphous  powder, 
insoluble  in  nitric  acid.  The  product  should  lose  no  lead  by 
digestion  with  nitric  acid,  but  should  dissolve  to  a  clear  solution 
in  nitric  acid  on  the  addition  of  potassium  nitrite. 


15.     Antimony  Trichlorid  SbCl%. 
( By-  p rod u ct :    Sodium  Sulfid,  Naz S. ) 

Raw  fiaterials:  Floated  stibnite,  concentrated  hydrochloric 
acid,  caustic  soda. 

The  decomposition  of  stibnite  by  hydrochloric  acid  is  depend- 
ent upon  the  concentration  of  the  acid  and  the  temperature  of 
the  reaction. 

Hydrochloric  acid  containing   25   per  cent.   HCl  or  more, 
decomposes  stibnite  slowly,  even  in  the  cold,  but  more  rapidly 
on  heating: 
( 1 )  8b&  +  6  HCl  =  2Sb  C13  +  3H2S. ' 

Exercise  :     Convert  100  grams  of  stibnite  into  antimony  tri- 


1  This  is  a  reversible  reaction.  From  solutions  of  antimony  trichlorid 
in  dilute  hydrochloric  acid,  hydrogen  sulfid  precipitates  antimony  sulfid: 

2SbCls  +  3H2S  =  Sb2SB  -f  6 HCL 

If  the  strength  of  the  hydrochloric  acid  be  such  that  the  acid 
decomposes  the  antimony  sulfid  when  hot  but  not  when  cold,  then  the  clear 
hot  solution  is  apt  to  precipitate  the  red  antimony  sulfid  on  cooling,  unless 
the  hydrogen  sulfid  has  been  completely  boiled  out  of  the  solution. 


ANTIMONY    TRICHLORID.  41 

chlorid,  and  obtain  as  a  by-product  1  liter  of  5  per  cent,  aqueous 
solution  of  sodium  sulfid. 

Operation:  Dissolve  in  800  cc  water  the  quantity  of  caustic 
soda  required  by  equations  (2)  and  (3) ;  divide  the  solution  into 
two  equal  portions  and  place  one  in  the  retort  C  (Fig.  1,  page  4)  ; 
the  wash  bottle  B  contains  water.  The  finely  powdered  (floated) 
stibnite  is  placed  in  the  flask  A  and  about  twice  the  quantity  of 
concentrated  hydrochloric  acid  added,  which  is  required  by  the 
equation  (1).  (Why  is  more  than  the  theoretical  quantity  re- 
quired ?)  The  decomposition  is  aided  by  a  gradually  increasing 
heat,  and  is  complete  when  the  evolution  of  gas  ceases. 

Time  of  Operation:     About  2  hours. 

If  the  stibnite  contains  compounds  of  arsenic,  the  easily 
volatile  arsenious  chlorid,  AsCl^  passes  over  with  the  steam  into 
the  wash  bottle,  where  arsenious  sulfid  will  be  precipitated.1 

The  retort  will  now  contain  a  solution  of  sodium  hydrosulfid, 
and  to  this  the  reserved  portion  of  sodium  hydroxid  is  added. 
The  retort  is  then  rinsed  with  sufficient  water  to  make  the 
solution  up  to  1  liter.2 

(2)  NaOH+  H2S  =  NaSH+  H20. 

(3)  NaSH+  NaOH  =  Na2S  +  HZ0. 

After  the  undissolved  sand,  etc.,  in  the  flask  has  completely 
settled  to  the  bottom,  the  solution  is  poured  from  the  deposit  into 
a  tubulated  retort  (A,  Fig.  11),  a  thermometer  inserted  in  the 
tubulature,  and  the  larger  portion  of  the  water  and  hydrochloric 
acid  distilled  over  into  receiver  B.  The  tubulature  b  contains 
a  tube  c  to  lead  away  the  hydrochloric  acid  fumes.  When  the 
thermometer  reaches  120°  the  liquid  contents  of  the  retort  are 
transferred  to  a  distillation  flask  (A,  Fig.  12)  and  submitted  to 


1  This  behavior  should  be  noticed.     If  iron  sulfid  contains  arsenic,  the 
hydrogen   sulfid  made  from  it  is  liable   to  contain  arsenic.     This  is   of 
especial  importance  in  forensic  work. 

2  The  solution  of  sodium  sulfid  is  to  be  preserved  for  Preparation  18. 


42 


ANTIMONY    TRICHLORID. 


fractional  distillation.  The  portion  distilling  below  180°,  and 
that  from  this  point  up  to  220°,  are  collected  separately  and  the 
distillate  is  then  tested  by  letting  a  drop  fall  on  a  watch  glass  to 
see  if  it  solidifies.  If  this  is  the  case,  the  receiver  B  is  to  be 
again  changed  and  the  distillation  continued  so  long  as  anything 
passes  over.  Care  must  be  used  to  see  that  the  distillation  tube 
does  not  become  stopped  by  solidified  antimony  trichlorid ;  should 
this  happen  the  mass  is  to  be  melted  by  the  flame.  In  the  retort 
there  remains  a  brownish-yellow  residue  of  basic  iron  chlorid, 
derived  from  the  iron  contained  in  the  stibnite.  The  distil- 


Fig.  11.  Concentration  of  Antimony 
Trichlorid. 


Fig.  12.  Fractional  Distillation 
of  Antimony  Trichlorid. 


lates  are  generally  somewhat  yellowish  in  color  from  iron  chlorid 
carried  over.  From  the  liquid  portions  which  passed  over  first 
further  quantities  of  the  solid  product  may  be  obtained  by 
repeated  fractional  distillations;  by  finally  redistilling  the  united 
solid  products  a  colorless  preparation  is  obtained,  solidifying  to 
a  crystalline  mass.  This  is  preserved  in  a  flask  (0,  Fig.  12) 
whose  tubular  neck  can  be  sealed  by  fusing. 

The  yield  cannot  correspond  to  the  theoretical,  because  anti- 
mony trichlorid  is  somewhat  volatile  with   superheated  steam 


FLUOSILICIC   ACID.  43 

and  therefore  it  passes  over  into  the  latter  portions  of  the 
aqueous  distillate;  the  yield  depends  further  upon  the  purity 
of  the  stibnite. 

Properties  :  Antimony  trichlorid  forms  a  white  crystalline 
mass,  melting  at  73°  and  boiling  at  221°.  It  deliquesces 
gradually  in  the  air,  absorbing  moisture;  it  is  miscible  with 
small  quantities  of  water,  but  with  larger  amounts  it  is  decom- 
posed into  antimony  oxychlorid  and  hydrochloric  acid. 


1  6.    Fluosilicic  Acid. 

H2SiF<.. 
(  By-prod  uct  :     Silicic  acid.  ) 

Raw  Materials:  Calcium  fluorid  (fluorspar),  silicic  acid 
(kieselguhr  [infusorial  earth],  or  quartz  sand),1  concentrated 
sulfuric  acid,  (about  1  kilo  of  mercury).  The  hydrofluoric  acid 
liberated  by  the  action  of  concentrated  sulfuric  acid  on  fluor- 
spar: 

(1)  S2SO,  4-  CaF2  =  CaSO±  -f  2HF, 

reacts  upon  silicic  acid  present  in  the  mixture  according  to  the 
equation  : 

(2)  4HF  -f  Si  02  =  SiF±  -f-  2H2  0. 

The  water  is  retained  by  the  excess  of  concentrated  acid 
present,  while  the  silicon  tetrafluorid  is  led  into  water,  where  it 
is  immediately  decomposed  into  gelatinous  silicic  acid  which  is 
precipitated,  and  fluosilicic  acid. 
(  3  )  SSiF, 


1  The  silicic  acid  obtained  as  a  by-product  in  a  previous  preparation 
can  be  used. 

[2Prof.  T.  H.  Norton  has  shown  that  this  equation  should  probably  be  : 

-f 


44  FLUOSILICIC   ACID. 

Exercise:  Convert  the  calcium  fluorid  obtained  as  a  by- 
product from  the  preparation  of  alumina  and  soda  from  cryolite 
(page  16),  or  100  grams  of  fluorspar,  into  fluosilicic  acid. 

The  Apparatus  (Fig.  13)  used  consists  of  the  vessel  A  and  the  glass 
cylinder  J5,  holding  about  a  liter,  which  are  connected  by  the  tubes  c  and 
d.  As  a  vessel  for  the  evolution  of  SiF^  a  stone  mineral  water  bottle 
holding  about  f  liter  answers  well.  This  bottle  stands  in  an  iron  pot  sur- 
rounded by  sand,  which  serves  as  a  sand  bath,  and  the  pot  rests  upon  a 

Fletcher  burner  F.  The  T-tube 
d  should  be  as  large  as  possible, 
and  is  fitted  into  the  bottle  by  a 
cork  or  by  plaster  of  Paris.  The 
lower  opening  of  the  tube  should 
have  a  hole  filed  in  the  side,  and 
the  upper  opening  is  closed  by  a 
cork.  This  cork  should  fit  rather 
loosely,  so  that  if  the  tube  c  e  be- 
comes stopped,  it  can  act  as  a  safety 
valve.  The  glass  tube  c  with  its 
enlarged  end  e  reaches  to  the  bot- 
tom of  the  glass  cylinder  B. 

Besides  the  above  there  are 


No.  13.  Prep'n  of  Fluosilicic  Acid.       necessa7>  a  strainer 

17)  of  flannel,1  and  a  glass  spoon, 

which  can  be  made  before  the  blast  lamp.  A  ball  is  blown  on  the  end  of 
a  glass  tube,  and  then  having  softened  one  side  of  the  ball  in  the  flame, 
the  air  is  rapidly  sucked  out. 

Operation  :  The  silica  is  advantageously  used  in  a  very  finely 
divided  condition,  such  as  kieselguhr  or  infusorial  earth,  and 
one-fourth  more  should  be  used  than  is  theoretically  required. 
(If  quartz  sand  is  used  double  the  quantity  should  be  taken.) 
The  sulfuric  acid  must  be  in  large  excess  (why?)  ;  to  100  grams 
of  calcium  fluorid  use  at  least  500  grams  sulfuric  acid.  The 
calcium  fluorid  and  the  silicic  acid  should  be  previously  heated 

1  When  the  liquid  is  acid,  the  cloth  for  the  strainer  should  be  of  ani- 
mal fibre  (wool),  when  alkaline,  of  vegetable  fibre  (cotton  or  linen), 
(compare  Preparation  6,  page  16.  ) 


FLUOSILICIC   ACID.  45 

in  an  iron  dish  until  every  trace  of  moisture  is  expelled,  and 
every  trace  of  organic  matter  in  the  kieselguhr  is  destroyed. 
After  cooling  they  are  to  be  finely  ground  in  a  mortar,  inti- 
mately mixed,  and  then  poured  into  the  bottle.  The  apparatus 
is  then  set  up,  great  care  being  taken  that  the  interior  of  the 
tubes  c  and  d  is  quite  dry.  Into  the  glass  cylinder  pour  enough 
mercury  to  just  close  the  opening  of  the  tube  e  and  then  fill 
the  cylinder  four-fifths  full  of  water.  Pour  the  sulfuric  acid 
into  the  bottle  through  the  T-tube  by  means  of  a  long-necked 
funnel,  close  the  opening  of  the  T-tube  and  light  the  flame 
under  the  sand  bath.  The  evolution  of  gas  begins  immediately1 
and  is  easily  controlled.  After  the  air  has  been  expelled,  the 
ascending  bubbles  become  covered  with  a  film  of  silicic  acid. 
This  collects  at  first  at  the  surface  as  a  gelatinous  mass  and 
gradually  fills  the  cylinder.  When  the  contents  of  the  cylinder 
become  so  thick  that  the  gas  bubbles  find  their  way  to  the  sur- 
face with  difficulty,  portions  should  be  removed  to  the  strainer 
with  the  glass  spoon,  and  fresh  portions  of  water  added. 
Toward  the  end  of  the  reaction,  which  may  be  recognized 
by  the  slower  evolution  of  gas,  tubes  of  silicic  acid  are  gener- 
ally formed  from  the  surface  of  the  mercury,  and  through  these 
the  gas  ascends  undecomposed. 

Time  of  Operation  :   2  to  3  hours. 

The  contents  of  the  cylinder  are  now  poured  off  from  the 
mercury  on  to  the  strainer  and  thoroughly  washed.  The  silicic 
acid  is  then  squeezed  out,  removed  from  the  strainer  and  dried. 
The  percolate  is  clarified  by  filtering  through  paper. 

The  estimation  of  the  strength  of  the  solution  in  fluosilicic 
acid  is  best  determined  by  titration  with  normal  alkali  at  a 
boiling  temperature,  litmus  being  used  as  an  indicator. 


1  If  the  calcium  fluorid  was  not  thoroughly  washed,  sodium  carbo: 
be  present,  owing  to  the  decomposition  of  the  aluminate  by  the 


sodium  carbonate 
ainate  by  1 
bon  dioxid  of  the  air.     In  this  case  carbon  dioxid  will  be  evolved. 


46  CRYSTALLIZED    SILICON. 

HJMF,  +  6KOH=6KF+  SiO,  +  4H.O, 
1  cc  normal  alkali  corresponds  to  0.024  gram  H2SiF6. 

The  yield  is  about  80  per  cent,  of  the  theoretical. 

Properties  :  Fluosilicic  acid  cannot  be  concentrated  by  evap- 
oration, since  it  is  gradually  decomposed  into  silicon  tetrafluorid 
and  hydrofluoric  acid.  In  not  too  dilute  solutions,  sodium  and 
potassium  hydroxids  produce  colorless  translucent  precipitates 
of  sodium  and  potassium  fluosilicates.  Barium  fluosilicate  is 
insoluble  even  in  hydrochloric  acid,  but  is  easily  distinguished 
from  barium  sulfate  by  its  crystalline  structure  when  seen  under 
the  microscope. 


17.     Crystallized    Silicon. 

(Intermediate  Product  :  Potassium  Fluosilicate.} 

Raw  Materials  :  Fluosilicic  acid,  potassium  hydroxid,  alum- 
inum filings,  hydrochloric  acid. 

On  heating  potassium  fluosilicate  with  aluminum,  silicon  is 
obtained,  together  with  potassium  fluorid  and  aluminum  fluorid: 

3KzSiF&  -f  4AI  =  SSi  +  6KF  '  +  J^AlFy 

If  more  aluminum  is  used  than  is  required  by  the  equation, 
the  fused  excess  dissolves  the  silicon,  and,  on  cooling,  the  latter 
separates  out  in  small  crystals. 

Exercise  :  Obtain  the  silicon  in  the  fluosilicic  acid  made  in 
Preparation  16. 

Operation  :  Neutralize  the  fluosilicic  acid  exactly  with  a 
concentrated  solution  of  potassium  hydroxid  : 

2KOH=  KSiF       2H  0. 


This  is  easily  accomplished  if  one  reserve  a  small  portion  of 
the  acid  to  add  to  the  balance  when  it  has  been  neutralized. 


RECOVERY  OF  TIN  FROM  TIN  PLATE.  47 

The  translucent,  iridescent  precipitate  soon  settles;  after  fil- 
tration by  suction  and  drying,  the  potassium  fluosilicate  is 
obtained  as  a  white  amorphous  powder. 

This  is  next  ground  very  intimately  with  one-third  its  weight 
of  aluminum  filings,  placed  in  a  Hessian  crucible,  covered  with 
a  further  quantity  of  aluminum,  and  the  whole  then  heated 
about  a  half  hour  at  a  red  heat. 

On  breaking  the  crucible,  a  larger  regulus  is  found,  together 
with  smaller  masses  of  grayish  color,  on  whose  surface  little 
shining  silicon  crystals  can  be  seen,  presenting  generally  under 
the  lens  the  appearance  of  octaedra.  These  metallic  masses 
are  freed  mechanically  from  the  slag,  and  then  treated  with 
hydrochloric  acid.  The  aluminum  dissolves,  leaving  the  silicon 
in  grayish  black,  graphite  like,  shining  crystal  flakes. 

Yield  :  About  one-tenth  of  the  potassium  fluosilicate  used 
(—  ?  per  cent  of  theoretical  product?) 

Properties  :  Crystallized  silicon  is  not  attacked  by  acids, 
but  solutions  of  potassium  and  sodium  hydroxids  dissolve  it 
with  evolution  of  hydrogen  and  formation  of  silicates.  It  is 
harder  than  glass  and  does  not  burn  when  heated  on  platinum 
foil.  It  can  be  freed  from  any  silica  which  may  be  mingled 
with  it  by  treating  with  hydrofluoric  acid  in  a  platinum  dish. 


1 8.    Recovery  of  Tin  from  Tin  Plate. 

(Chief  Product:   Tin;  Secondary  Product:  Potassium  Oyanate.) 

Raw  Materials  :   Scrap  tin  plate,  sodium  sulfid,  flowers  of 
sulfur,  crude  hydrochloric  acid,  potassium  cyauid. 

Tin  .plate  contains   4   to   6   per  cent,  of  tin,  which  can   be 
separated  from  the  iron  by  treatment  with  sodium  sulfid  and 
sulfur.     Soluble  sodium  thiostannate  is  formed: 
(1 )  Sn  +  Na,S  +  88  =  Na,SnS3, 


48  RECOVERY   OF   TIN   FROM   TIN    PLATE. 

from  which  tin  sulfid  is  precipitated  by  acids: 

(2)  NaJSnSt  +  2HCI  =  SnS2  +  H2S  -\-  2  Na Cl. 
By  roasting  in  the  air,  tin  sulfid  is  oxidized  to  tin  oxid : 

(3)  SnS,  +  60  =  Sn02-{-  280^ 

By  fusion  with  potassium  cyanid,  tin  oxid  is  reduced  to  tin: 

(4)  Sn  0,  +  2KCN=  Sn  '+  2KCNO. 
Exercise:    Recover  the  tin  from  one  kilo  of  tin  plate  scrap. 
Operation :    Place  the  tin  scrap,  cut  into  small  pieces,  in  an 

iron  vessel  and  add  the  theoretical  quantity  of  sodium  sulfid 
solution  from  Preparation  15,  required  for  the  formation  of 
sodium  thiostannate,  assuming  that  the  scrap  contains  6  per 
cent.  tin.  Add  the  required  quantity  of  flowers  of  sulfur  and 
sufficient  water  to  cover  the  scraps.  Heat  to  boiling  and  con- 
tinue the  boiling  with  the  addition  of  water  from  time  to  time 
to  replace  that  lost  by  evaporation.  In  one  or  two  hours  all  the 
tin  should  be  removed  frdm  the  iron.  Cool  and  pour  the 
yellow  liquid  from  the  iron,  filter  if  necessary  through  a 
sand  filter,1  heat  to  boiling  and  precipitate  with  concentrated 
hydrochloric  acid  (crude).  Strain  the  precipitated  tin  sulfid 
through  flannel,  squeeze  and  dry.2  The  tin  sulfid  is  then 
spread  in  a  thin  layer  upon  an  iron  plate  and  roasted  over  a 
Bunsen  burner.  The  operation  is  complete  when  a  sample, 
heated  in  an  open  tube,  gives  off  no  fumes  of  sulfur.  The  tin 
oxid  contains  some  sodium  chlorid,  which  is  now  removed  by 
boiling  with  water. 

The  reduction  of  the  tin  oxid  is  carried  out  best  in  a  Hessian 
cj ucible  in  which  the  amount  of  potassium  cyanid  required  by 

1  The  filtrate  is  often  colored  greenish-black  by  the  presence  of  a  little 
Na^Fe^S2.    This  is,  however,  in  no  way  detrimental  in  the  subsequent 
operations. 

2  The  voluminous  precipitate  is  washed  with  difficulty.     It  is,  there- 
fore, easier  to  purify  the  roasted  product.     The  tin  sulfid  "is  best  dried  by 
spreading  out  on  porous  tiles  or  brickjg. 


CARBAMID.  49 

equation  (4)  has  been  fused.  The  thoroughly  dried  tin  oxid  is 
added  little  by  little,  the  melt  being  from  time  to  time  stirred 
with  an  iron  rod,  and  finally  heated  until  the  contents  have 
come  to  a  quiet  fusion. 

After  cooling,  the  crucible  is  broken,  the  regulus  of  tin 
separated  from  the  slag  (potassium  cyanate),  and  the  latter 
saved  for  the  following  preparation. 

Yield :     30  to  40  grams  of  tin. 


19.     Carbamid  (Urea). 

CO 


Raw  Materials:     Potassium  cyanate,    dilute  sulfuric  acid, 
ammonia,  alcohol. 

Potassium  cyanate  reacts  with  ammonium  sulfate,  forming 
potassium  sulfate  and  ammonium  cyanate: 

2KCNO  +  (JVB"4)8  SO,  =  K2SO,  +  2NH.CNO, 
and  ammonium  cyanate  in  aqueous  solution  undergoes  when 
heated  an  intermolecular  change  into  carbamid  : 

NH 


Exercise:  Convert  the  potassium  cyanate  obtained  as  a  by- 
product in  Preparation  18  into  urea. 

Operation:  Boil  the  slag  from  the  tin  regulus  and  the 
crucible  with  a  solution  of  ammonium  sulfate,  filter  and  evapo- 
rate the  filtrate  to  dryness  in  a  porcelain  dish  on  a  water  bath. 
The  ammonium  sulfate  is  prepared  by  neutralizing  with  ammonia 
the  quantity  of  sulfuric  acid  corresponding  to  the  potassium 
cyanid  used  in  Preparation  18. 

The  separation  of  the  urea  from  the  potassium  sulfate  (and 
from  any  excess  of  ammonium  sulfate  present)  is  accomplished 


50  CARBAMID. 

by  boiling  the  residue  with  alcohol  in  a  reflux  condenser.     (Fig. 
14. )     The  round-bottomed  flask  A,  which  contains  the  residue 


Fig.  14.     Heating  with  a  Keflux  Condenser. 

and  about  0.251  alcohol  (sp.  gr.  0.82),  is  connected  with 
the  cooler  B  and  heated  on  a  water  bath.  After  the  boil- 
ing of  the  alcohol  has  continued  for  half  an  hour,  the  flame 
under  the  water  bath  is  extinguished,  the  flask  detached  from 


Fig.  15.     Distillation  of  the  Alcohol. 

the  cooler  and  the  solution  filtered  into  a  short-necked  flask,  C. 
Care  should  be  used  that  the  undissolved  matter  which  settles 


BARIUM    NITRATE.  51 

rapidly  to  the  bottom  of  the  flask  is  not  poured  out  on  the  filter. 
The  flask  C  is  then  connected  by  a  tube  bent  at  an  acute  angle 
with  the  cooler  (Fig.  15)  and  the  flask  containing  the  residue  is 
used  as  a  receiver  at  the  lower  end  of  the  condenser.  The 
alcohol  is  distilled  off  until  only  a  few  cubic  centimeters  remain. 
This  solution  is  poured  into  a  small  crystallizing  dish.  On 
cooling,  the  urea  crystallizes  in  flat  prisms.  Repeat  the  extrac- 
tion of  the  residue  in  the  flask  with  the  distillate  until  no  more 
urea  is  obtained.  Two  extractions  usually  suffice. 

Yield  :  30  to  40  grams  of  urea  from  60  grams  potassium 
cyanid,  instead  of  ?  grams  theoretical. 

Properties  of  Urea:  Melts  on  platinum  foil  and  decom- 
poses on  further  heating,  leaving  no  residue.  Easily  soluble  in 
alcohol,  more  soluble  in  water.  From  the  aqueous  solution, 
nitric  acid  precipitates  urea  nitrate,  CO  (NH,'),,  HNO^  which 
is  difficultly  soluble,  especially  in  nitric  acid.  With  mercuric 
nitrate  an  insoluble  compound  is  formed, 


which  is  used  for  determination  of  urea  by  Liebig's  method. 
On  treatment  with  sodium  hypobromite,  NaOBr,  (Knop-Hiifner 
method  of  determining  urea)  or  nitrous  acid,  carbamid  is  decom- 
posed into  carbon  dioxid  and  nitrogen: 

CO(NH2-)2  +  SNaOBr  =  CO,  +  JV2  +  2H20  +  SNaBr. 
CO(NH2\  +  VHNO,  =  CO,  +  2N,  +  3H,0. 


20.     Barium    Nitrate. 


Raw  Materials  :   Powdered  heavy  spar   (barite),  charcoal 
powder,  nitric  acid. 

Barium  sulfate  is  decomposed  by  carbon  at  a  red  heat: 
(1)  BaSOt  +  4C=BaS+  4CO. 


52  HYDRATED   BARIUM   PEROXID. 

Barium  sulfid  is  formed  which  dissolved  in  nitric  acid  with 
the  formation  of  barium  nitrate : 

(2)  BaS  +  2HN05  =  Ba(NO,\  4-  H2S. 

Exercise  :    Convert  100  grams  of  barite  into  barium  nitrate. 

Operation  :  A  mixture  of  powdered  barite  and  very  finely 
powdered  charcoal,  in  the  proportions  given  by  equation  (1),  is 
ground  together  very  thoroughly  and  heated  to  redness  in  a 
Hessian  crucible  about  an  hour.  On  cooling,  the  contents  of 
the  crucible  should  form  a  reddish  grey,  porous,  friable  mass.1 
This  is  then  pulverized  and  added  in  small  portions  to  the  nitric 
acid  required  by  equation  (2).  The  nitric  acid  should  be  diluted 
with  sufficient  water  to  dissolve  in  the  cold  all  the  barium  nitrate 
formed.  At  this  dilution  very  little  of  the  evolved  hydrogen 
sulfid  is  oxidized  to  sulfuric  acid,  hence  there  will  be  no  re-for- 
mation of  barium  sulfate.  When  all  the  barium  sulfid  has 
been  added  to  the  nitric  acid,  the  hydrogen  sulfid  is  expelled 
by  heat,  the  solution  filtered,  and  evaporated  to  crystalliza- 
tion. A  second  crop  of  crystals  is  obtained  on  further  evap- 
oration and  the  rest  of  the  salt  can  be  precipitated  by  alcohol. 

Yield  :  80  to  90  per  cent,  of  the  theoretical. 

Properties:   White,  brilliant  octaedra,  insoluble  in  alcohol. 


21.     Hydrated  Barium  Peroxid. 

J3a02,  8  aq. 

(Intermediate  Product :  Barium  Oxid.} 

Raw  Materials  :    Barium  nitrate,  barium  hydroxid,  hydro- 
chloric acid,  ice. 

1  If  the  contents  of  the  crucible  are  still  pulverulent  they  must   be 
ground  again  and  heated  a  second  time. 


HYDRATED  BARIUM  PEROXID.  53 

When  barium  nitrate  is  heated  to  redness,  barium  oxid  is 
formed : 

(1)  £a(NOJ9=BaO+2NOt+  0  ; 

when  a  current  of  air  is  led  over  the  barium  oxid,  the  peroxid 
is  formed : 

(2)  5aO-f  0=Ba02. 

If  barium  peroxid  is  treated  carefully  with  hydrochloric  acid 
in  the  cold,  an  aqueous  solution  of  hydrogen  peroxid  is  formed : 

(3)  Ba02  +  2HCl  =  H202  -f  Bad, ; 

crystalline  hydrated  peroxid  of  barium  is  precipitated  on  the 
addition  of  baryta  water  to  this  solution  of  hydrogen  peroxid : 

(4)  H2 02  +  Ba( OH)2  +  6H20  =  Ba02,  8  aq. 

Exercise  :  Convert  the  barium  nitrate  obtained  in  Prepara- 
tion 20  into  hydrated  barium  peroxid. 

Operation  :  The  barium  nitrate  is  gradually  heated  in  a 
Hessian  crucible  until  it  reaches  a  low  red  heat.  On  cooling, 
the  contents  of  the  crucible  appear  as  a  greenish  gray,  hard, 
porous  mass,  which  can  generally  be  separated  from  the  walls 
of  the  crucible  only  by  breaking  it.  This  mass  should  be  imme- 
diately placed  in  tight,  dry  receptacles,  to  prevent  its  absorption 
of  moisture  from  the  atmosphere.  A  small  sample  should  be 
tested  by  heating  in  a  hard  glass  tube,  and  in  case  brown  gases 
are  given  off,  the  whole  quantity  must  be  reheated  in  a  crucible. 

To  prepare  the  barium  peroxid,  a  hard  glass  tube1  of  1.5  cm 
diameter  is  filled  with  pieces  of  barium  oxid  the  size  of  peas, 
each  end  is  loosely  closed  with  a  wad  of  asbestos  and  fitted  with 
a  cork  containing  a  glass  tube  to  which  a  rubber  tube  is  at- 
tached. All  the  fittings  should  be  air  tight.  The  tube  is  then 


1  The  length  of  the  tube  depends  upon  the  length  of  the  combustion 
furnace  used.    After  filling,  the  tube  is  to  be  weighed. 


54  HYDRATED   BARIUM    PEROXID. 

heated  in  a  combustion  furnace  to  a  dull  red  heat,1  while  a  cur- 
rent of  air  is  led  through  it.  In  order  to  be  able  to  judge  of 
the  rapidity  of  the  air  current,  a  wash  bottle  containing  con- 
centrated sulfuric  acid  should  be  placed  at  the  end  of  the  tube 
into  which  the  air  enters. 

The  simplest  method  of  leading  the  air  through  the  tube  is  by  the 
use  of  a  two-flask  (Muencke)  aspirator,  or  a  filter  pump. 
5  liters  air  correspond  to  about  1  liter  oxygen. 

When  the  tube  has  been  cooled  it  is  weighed  ;  the  operation, 
which  requires  two  to  three  hours,  is  to  be  considered  finished 
when  the  increase  in  weight  corresponds  approximately  to  the 
theory. 

The  amount  of  hydrochloric  acid  corresponding  to  equation 
(3)  is  now  diluted  with  water  until  its  strength  is  1  or  2  per  cent. , 
and  is  cooled  by  the  addition  of  ice.  The  powdered  barium 
peroxid  is  added  in  small  portions.  The  temperature  of  the 
solution  should  be  kept  at  0°  by  further  quantities  of  ice.  If 
all  the  barium  peroxid  does  not  dissolve,  any  deposit  is  to  be 
rubbed  in  a  porcelain  mortar  with  repeated  portions  of  the 
solution,  or,  if  necessary,  with  the  addition  of  small  quantities 
of  dilute  hydrochloric  acid,  until  no  more  dissolves.  The  united 
acid  solutions  are  now  neutralized  with  a  solution  of  barium 
hydroxid  (baryta  water),  or  even  made  very  slightly  alkaline, 
the  impurities  (alumina,  iron  oxid  from  the  crucible)  being  as 
a  result  precipitated.  The  solution  is  then  filtered,  and  by 
further  addition  of  baryta  water,  hydrated  barium  peroxid  is 
precipitated.  This  is  filtered,  washed  and  preserved  in  a  moist 
condition  (en  pate). 


1  At  a  dull  red  heat  barium  oxid  absorbs  oxygen  from  the  air  (equa- 
tion (2));  at  a  bright  red  heat  the  reverse  reaction  takes  place,  in  which 
barium  peroxid  is  decomposed  into  barium  oxid  and  oxygen,  (BaO2= 
BaO+0).  The  technical  method  of  obtaining  oxygen  from  the  air  de- 
pends upon  these  reactions. 


HYDROXYLAMIN    HYDROCHLORID.  55 

The  yield  is  determined  by  titration  with  potassium  perman- 
ganate : 

.2  -f  2KMnO±  -f 

0 


Properties  :  Brilliant  quadratic  flakes;  insoluble  in  water; 
decomposed  on  standing  (even  in  a  moist  condition)  into  barium 
hydroxid  and  oxygen.  If  a  few  crystals  are  dissolved  in  dilute 
hydrochloric  acid,  covered  with  ether,  and  then  a  trace  of 
potassium  chromate  is  added,  perchromic  acid  is  formed,  which, 
when  the  solution  is  shaken  with  the  ether,  imparts  to  it  a  violet 
color. 


22.    Hydroxylamin  Hydrochloric!,1 

HONH2,Hd. 
(Intermediate  Product:  Potassium  Hydroxylamin  Disulfonate  [wtfaxotatt].} 

Raw  Materials:  Soda,  concentrated  sulfuric  acid,  potas- 
sium nitrite,  potassium  chlorid,  barium  chlorid,  alcohol,  char- 
coal, ice. 

If  one  molecule  of  potassium  nitrite  reacts  at  a  temperature  of 
0°  with  two  molecules  of  hydrogen  sodium  sulfite,2  there  is 
formed  the  sodium  salt  of  hydroxylamin  disulfonic  acid  : 


(1) 

and  this  in  turn  reacts  with  potassium  chlorid  to  form  the  diffi- 
cultly soluble  potassium  salt: 

(2)    HON(SO,Na\  -f  2KCI  =  HON  (S03K\  +  2NaCl. 
If  the  aqueous  solution  of  the  potassium  hydroxylamin  disul- 


1  Discovered  by  W.  Lessen  in  1865,  and  first  prepared   from   ethyl 
nitrite. 

2  According  to  F.  Easchig  (D.  E.  Patent  41,987.) 


56  HYDROXYLAMIN   HYDROCHLORID. 

fonate  is  boiled  with  barium    chlorid,    the  following  reaction 

takes  place: 

(3)  HON(SO,K)2  +  2Ba  C12  +  2H20  = 

HONH^HCl  4-  2BaSO,  +  2KCI  +  H Cl. 

The  hydroxylamin  hydrochlorid  can  be  separated  from  the 
potassium  chlorid  by  alcohol,  in  which  the  former  is  soluble  and 
the  latter  insoluble. 

Exercise:  Convert  106  grams  of  calcined  soda  into  hydrogen 
sodium  sulfite  and  use  a  solution  of  the  latter  to  prepare  the 
hydroxylamin  hydrochlorid. 

Operation:  Into  a  cold  saturated  solution  of  soda,  lead  a 
rapid  current  of  sulfur  dioxid  until  a  portion  of  the  solution, 
even  after  shaking,  still  smells  strongly  of  sulfur  dioxid. 

Time  of  Operation :     2  to  3  hours. 

Na,  CO,  +  280,  +  H20  =  2HNaSO,  +  CO.. 

For  the  preparation  of  sulfur  dioxid  fill  a  round-bottomed 
liter  flask  to  the  neck  with  coarse  pieces  of  dried  charcoal;  add 
concentrated  sulfuric  acid  until  the  flask  is  half  full,  and  heat 
on  a  sand  bath  (apparatus  as  in  Fig.  1). 

2H,SO,  +  C  =  2SO,  +  CO,  +  2H,  0. 

Dissolve  the  amount  of  potassium  nitrite  required  by  equation 
(1)  in  0.5  liter  of  water,  cool  the  solution  and  also  that  of  the 
hydrogen  sodium  sulfite  to  0°,  by  adding  pieces  of  ice.  Now 
surround  the  flask  containing  the  potassium  nitrite  solution  with 
broken  ice,  and  add  the  sulfite  solution  little  by  little,  so  slowly 
that  the  temperature  of  the  mixture  does  not  rise  appreciably 
above  0°.  Make  a  cold  saturated  solution  of  the  amount  of  potas- 
sium chlorid  required  to  decompose  the  sodium  salt  according  to 
equation  (2),  cool  with  ice,  add  to  the  mixture,  and  let  the  whole 
stand  over  night.  The  next  morning  filter  off  the  solid  crystal- 
line crusts  of  hydroxylamin  disulfonate  of  potassium  which  have 
separated  out,  and  after  drying  on  filter  paper,  weigh.  (The 


PHOSPHORUS  PENTACHLORID.  57 

yield  should  be  upwards  of  80  per  cent,  of  that  theoretically 
possible. ) 

To  convert  this  salt  into  hydroxylamin  hydrochlorid,  dissolve 
it  in  five  times  its  weight  of  hot  water,  add  the  requisite  quantity 
of  barium  chlorid,  according  to  equation  (3),  in  hot  saturated 
solution,  and  heat  the  mixture  for  an  hour  to  its  boiling  point. 
If  the  solution  still  contains  sulfuric  acid,  barium  chlorid  is 
added  until  a  filtered  test  shows  no  further  precipitate.  Filter 
off  the  barium  sulfate,  evaporate  on  the  water  bath  to  dryness 
and  extract  the  residue  repeatedly  with  0.25  liter  of  alcohol,  as 
in  the  case  of  urea  (see  page  50). 

Yield :     20  to  30  grams  of  hydroxylamin  hydrochlorid. 

Properties  of  Hydroxylamin  Hydrochlorid:  Crystallizes 
from  water  in  flakes,  from  alcohol  in  monoclinic  crystals.  It  is 
decomposed  on  heating  on  a  platinum  foil,  leaving  no  residue. 
The  aqueous  solution  acts  as  a  strong  reducing  agent  in  the  pres- 
ence of  an  alkali.  By  the  reduction  of  copper  salts  (compare 
page  20)  as  little  as  1  part  in  10,000  of  hydroxylamin  may  be 
detected.  (Lossen. ) 


23.     Phosphorus  Pentachlorid. 

PCI,. 

Raw  Materials  :  Red  phosphorus,  common  salt,  pyrolusite, 
concentrated  sulfuric  acid.  Chlorin  reacts  upon  red  phosphorus 
when  heated  with  the  formation  of  phosphorus  pentachlorid  : 


(1) 

Exercise  :    Convert  20  grams  of  red  phosphorus  into  phos- 
phorus pentachlorid. 

Apparatus  :  The  chlorin  is  evolved  in  a  round-bottomed  2  liter  flask; 


58 


PHOSPHORUS    PENTACHLORID. 


this  is  connected  with  a  wash  bottle  (Fig.  1,  A  and  B)  containing  concen- 
trated sulfuric  acid,  and  in  order  to  dry  the  chlorin  thoroughly,  the  wash 

bottle  is  in  turn  connected 
with  a  U-tube  or  a  scrubber 
(G  in  Fig.  16)  filled  with 
pieces  of  pumice  stone  satu- 
rated with  concentrated  sul- 
furic acid.  The  phosphorus 
is  placed  in  a  bulbed  tube 
D,  which  is  formed  by  fusing 
a  glass  tube  on  to  the  bottom 
of  a  round-bottomed  200 
cc  flask.  The  bulb  of  the 
tube  rests  upon  a  small  sand 


bath.       The  neck   of    the 
flask   should    be  15  to  20 


Fig.  16.   Prep,  of  Phosphorus  Pentachlorid. 

mm  wide,  but  as  short  as  possible,  and  it  projects  through  a  cork  stopper 
into  the  wide-mouthed  bottle  E,  which  serves  as  a  receiver.  The  cork  is 
also  pierced  by  a  glass  tube/,  from  30  to  40  cm  long  and  large  enough  to 
be  easily  cleared  out  by  a  glass  rod  in  case  it  becomes  stopped  up.  The 
arrangement  of  the  bulbed  tube  and  receiver  is  shown  in  the  figure.  The 
stopper  is  saturated  with  melted  paraffin,  and  need  not  close  the  bottle 
tightly.  The  apparatus  is  placed  under  a  good  draught. 

Operation  :  Place  the  thoroughly  dried  phosphorus  in  the 
bulbed  tube  D.  Fill  the  flask  for  preparing  chlorin  as  described 
in  Preparation  14  (page  39),  and  use  for  this  enough  material 
to  correspond  to  1^  times  the  chlorin  required  by  equation  (1). 
With  a  small  flame  under  the  sand  bath,  regulate  the  temper- 
ature to  correspond  with  the  evolution  of  chlorin.  At  the 
beginning  of  the  reaction,  and  in  case  the  chlorin  is  not  per- 
fectly dry,  hydrochloric  acid  and  phosphorus  oxychlorid  are 
given  off  through  the  tube1  /.  Later  the  flame  of  the  phos- 
phorus burning  in  the  stream  of  chlorin  is  seen.  Occasionally, 
especially  toward  the  end  of  the  operation,  the  bulbed  tube 
should  be  turned  on  its  axis,  in  order  to  drive  off  the  product 


1  Also  arsenic  trichlorid,  if  the  phosphorus  contains  arsenic. 


MONOCHLOROSULFURIC    ACID.  59 

which  has  sublimed  in  the  cooler  parts  of  the  tube.  The 
impurities  of  the  phosphorus  which  are  not  volatile  with  chlorin 
remain  in  the  bulbed  tube,  and  should  be  examined  qualita- 
tively. The  phosphorus  pentachlorid  which  is  deposited  in  the 
neck  of  the  bulbed  tube  is  easily  scraped  into  the  bottle. 

Time  of  Operation  :   2  to  3  hours. 

Yield  :   80  to  90  per  cent,  of  the  theoretical. 

Properties  :  Slightly  yellowish,  crystalline  mass,  fuming  in 
moist  air,  and  decomposed  by  a  little  water  into  hydrochloric 
acid  and  phosphorus  oxychlorid,  by  much  water  into  hydro- 
chloric and  phosphoric  acids: 

PCI,  +  H20  =  POCl,  +  2HCI 
PCI,  +  4&20  =  H,PO,  +  5HCI. 


24.     Monochlorosulfuric  Acid. 


(Sulfuryl  hydroxychlorid.) 

(Intermediate  product:    Anhydrous  sulfuric  add.) 

Raw  Materials:  Concentrated  sulfuric  acid,  fuming  sul- 
furic acid,  phosphorus  pentachlorid. 

If  phosphorus  pentachlorid  is  added  to  anhydrous  sulfuric 
acid,  there  is  formed  hydrochloric  acid,  monochlorosulfuric  acid 
and  phosphorus  oxychlorid  : 

HZSO,  +  PCI,  =  S02  °**+  PO  C13  +  HCL 

The  phosphorus  oxychlorid  reacts  further  with  sulfuric  acid 
forming  more  monochlorosulfuric  acid  and  metaphosphoric  acid: 

PO  Clt  +  2HZSO,  =  2SOZ  °H+  PO,  OH+  HCL 

Exercise  :  Convert  WO  grams  of  anhydrous  sulfuric  acid  into 
monochlorosulfuric  acid. 


60  MONOCHLOROSULFURIC     ACID. 

Operation:     1.    Preparation   of  anhydrous   acid 
Determine  by  titration: 

(a)  The  amount  of  H2SO±  and  H20  in  the  concentrated  sul- 
furic  acid; 

(6)  The  amount  of  H^SO±  and  S03  in  the  fuming  sulfuric  acid; 
and  mix  them  in  such  proportion  that  H2SO±  will  be  formed: 

(aH^+xH,  0)+(bH2SOt+  jsxSOt)  =  (a  +  b  +~x)H,80t. 

2.  Preparation  of  the  chlorid.  Pour  the  anhydrous  sulfuric 
acid  in  a  round-bottomed  1.5  liter  flask,  and  add  the  calculated 
quantity  of  phosphorus  pentachlorid  slowly  with  a  porcelain 
spatula. 

The  equation  to  be  used  is: 


8SO*  OH  +  PCl*  =  3SO*  c  +  P°2  OH  +  2HCL 
The  reaction  is  violent.  (Time  of  operation  \  hour.  )  After 
the  phosphorus  pentachlorid  has  all  been  added,  warm  the  flask 
upon  a  sand  bath  until  no  more  hydrochloric  acid  escapes,  then 
pour  the  product  into  a  tubulated  retort  (A,  Fig.  11)  and  distill 
the  monochlorosulfuric  acid  over  a  sand  bath.  The  tubulated 
receiver  should  be  perfectly  dry,  and  should  be  so  fitted  on  the 
retort  that  the  distillate  falls  freely  into  it.  When  the  ther- 
mometer reaches  160°  the  distillation  is  stopped.  The  residue 
in  the  retort  consists  of  metaphosphoric  acid  and  undecomposed 
sulfuric  acid.  The  distillate  should  be  redistilled  from  a  distill- 
ing flask  fitted  to  a  condenser  (Fig.  12)  and  should  be  preserved 
in  a  dry,  glass-stoppered  bottle. 

Yield  :     About  80  per  cent,  of  the  theoretical  quantity. 

Properties:  Boiling  point  153°.  Fumes  in  moist  air  and 
decomposes  gradually  into  sulfuric  acid  and  hydrochloric  acid; 
on  dropping  it  into  water,  decomposition  takes  place  with  explo- 
sive violence. 


AMIDOSULFONIC   ACID.  61 

25.     Amidosulfonic  Acid. 


(Sulfaminic  Acid.  ) 

A.  From  Monochlorosulfuric  Acid. 

(Intermediate  Product:    Barium  imidosulfonate.) 

Raw  materials  :  Monochlorosulfuric  acid,  ammonia  gas, 
barium  chlorid,  lime,  caustic  soda,  chloroform,  glycerol. 

Exercise  :  Convert  the  sulfuryl  hydroxychlorid1  obtained  in 
Preparation  24-  into  sulfaminic  acid. 

By  the  action  of  dry  ammonia  gas  in  the  cold  there  is  chiefly2 
formed  beside  ammonium  chlorid,  the  ammonium  salt  of  imido- 
sulfonic  acid: 

a  CSO.ONH, 

(1)          ®SO^H  +  5NH,  =  Nl  S02ONHt  +  2NH.CI. 

. 

Ammonium  imidosulfonate  is  quite  soluble  in  water  and  can- 

not be  separated  from  ammonium  chlorid  by  crystallization. 

On  adding  a  sufficient  quantity  of  barium  chlorid  to  the 
ammoniacal  solution,  the  basic  barium  salt  is  formed,  in  which 
the  imido-hydrogen  also  is  replaced  by  barium  : 


This  salt  is  insoluble  in  water  and  is  thus  readily  separated 
from  the  ammonium  chlorid. 

1  Generally  about    130  grams  of  sulfuryl    hydroxychlorid    will    be 
obtained  in  Preparation  24;  not  less  than  100  grams  should  be  used. 

2  There  is  also  formed,  especially  if  the  ammonia  is  not  quite  dry, 
more  or  less  sulfuric  acid: 


The  sulfuric  acid,  as  well  as  the  imidosulfonic  acid,  unites  with  the 
excess  of  ammonia  present  to  form  the  ammonium  salt.  Free  imidosul- 
fonic acid  is  not  known. 


62 


AMIDOSULFONIC    ACID. 


On  treating  the  basic  barium  salt  with  a  little  dilute  hydro- 
chloric acid,  the  crystalline  neutral  barium  salt  is  formed  : 


2HCl=2N 


Bad.,. 


On  boiling  with  water  this  is  decomposed  into  sulfaminic  acid 
and  barium  sulfate: 


S020 
H 


Ba 


CSO.OH 
=  N1  H 
Iff 


Apparatus :  The  flask  for  preparing  ammonia  is  connected  with  a  wash 
bottle  (A  and  B,  Fig.  1)  and  this  with  two  scrubbers  ( C  and  D,  Fig.  17), 
one  of  which,  <7,  is  filled  with 
pieces  of  lime  the  size  of  mar- 
bles, and  the  other,  Z),  with 
short  sticks  of  caustic  soda. 
From  D  the  dry  ammonia 
passes  through  the  T-tube  /, 
which  can  be  easily  pushed  up 
or  down,  and  whose  upper 
opening  is  closed  by  a  cork, 
into  the  flask  E,  which  holds 
from  one  to  two  liters.  This 
flask  is  connected  with  an  up- 
right condenser  (j?,  Fig.  14) 
which  enters  the  enlarged 


Prep,  of  Amidosulfonic  Acid. 


Fig.  17. 
opening  (Fig.  17)  of  the  bent  tube  g. 

Operation  :  Mix  the  sulfuryl  hydroxychlorid  with  2J  its 
volume  of  chloroform  dried  over  calcium  chlorid,  and  pour  the 
mixture  into  the  flask  E.  Ammonia  gas  may  be  prepared  as 
in  Preparation  2,  or  more  conveniently  by  gently  warming  con- 
centrated ammonia.  The  gas  must  be  in  a  completely  dry 
condition  when  it  enters  E.  With  the  apparatus  described,  a 
rapid  stream  of  ammonia  can  be  dried,  if  glycerol  is  used  in 
the  wash  bottle,  so  that  no  moisture  shall  be  carried  over  from 
this.  At  first  th  e  T-tube  is  given  the  position  shown  in  Fig. 


AMIDOSULFONIC   ACID.  63 

17,  that  is,  its  opening  is  just  above  the  surface  of  the  liquid; 
later  when  there  is  less  danger  of  its  becoming  stopped  up,  it 
may  enter  the  liquid. 

Ammonium  imidosulfonate  formed  on  leading  ammonia  into 
sulfuryl  hydroxychlorid,  is  insoluble  in  chloroform,  and  separates 
out,  together  with  the  ammonium  chlorid.  If  the  T-tube  or 
the  cooler  become  stopped,  they  can  be  easily  opened  by  a  glass 
rod. 

The  mixture  becomes  heated  by  the  reaction  and  the  chloro- 
form which  passes  off  is  condensed  in  the  cooler,  dropping  back 
into  the  flask  E.  The  completion  of  the  reaction  is  indicated 
by  the  contents  of  the  flask  becoming  cold,  and  smelling  dis- 
tinctly of  ammonia  after  standing. 

Time  of  Operation:   3  hours. 

Filter  off  the  chloroform  from  the  solid  residue,  free  it  from 
ammonia  by  shaking  with  water  in  a  separating  funnel,  and 
purify  by  distillation1  on  a  water  bath  (Fig.  15.)  A  small 
portion  of  the  residue  on  the  filter  paper  should  be  dissolved  in 
water  as  a  test.  If  heat  is  generated,  or  if  the  solution  has  an 
acid  reaction,2  the  whole  residue  must  be  replaced  in  the  flask 
and  ammonia  led  in  again,  without  connecting  with  a  condenser, 
until  an  average  sample,  rubbed  thoroughly  with  water  in  a 
mortar,  dissolves  with  alkaline  reaction.  The  dry  white  powder 
(ammonium  imidosulfonate  and  ammonium  chlorid)  is  dissolved 
in  the  flask  in  cold  water,  the  solution  weakly  acidified  with 
hydrochloric  acid,  and  a  cold  saturated  solution  of  so  much 
barium  chlorid  added  as  corresponds  to  1 J  times  the  weight  of 
sulfuryl  hydroxychlorid  used.  The  solution  is  then  filtered  from 
the  precipitated  barium  sulfate  into  a  vessel  containing  sufficient 
dilute  ammonia  to  keep  the  filtrate  alkaline ;  basic  barium  imido- 

1  In  this  way  f  of  the  chloroform  used  may  be  readily  recovered. 

2  This  is  the  case  if  undecomposed  sulfuryl  hydroxychlorid  is  present: 

S02  OHCl  +  H20  =  H.2SOt  +  HCl. 


64  AMIDOSULFONIC    ACID. 

sulfonate  then  separates  out.  This  is  filtered  off,  freed  as  far  as 
possible  from  moisture  by  pressure  between  filter  paper,  and 
suspended  in  water.  To  this  barium  salt,  suspended  in  as  little 
water  as  possible,  add  quickly  just  enough  (not  more!)  dilute 
hydrochloric  acid  for  solution.  The  walls  of  the  vessel  are  then 
rubbed  with  a  glass  rod  and  almost  immediately  the  neutral 
barium  imidosulfonate  (NH(SOs\Ba}  begins  to  crystallize  out. 
When  the  precipitation  is  complete,  the  salt  is  filtered  off  and 
pressed  between  paper.  To  form  the  amidosulfonic  acid,  the 
neutral  barium  imidosulfonate  is  suspended  in  an  equal  quantity 
of  water  by  weight,  and  the  mixture  warmed  on  the  water  bath 
(about  half  an  hour)  until  a  test  shows  no  more  crystals  under 
the  microscope.  The  barium  sulfate  is  filtered  off  and  the  filtrate 
(without  the  wash  water)  set  under  a  dessicator.  In  the  course 
of  one  or  two  days  the  amidosulfonic  acid  separates  out  in  beau- 
tiful crystals. 

B.     From  Hydroxylamin. 

Raw  Material  :   Hydroxylamin  hydrochlorid,  sulfur  dioxid. 
Sulfur  dioxid  reacts  upon  an  aqueous  solution  of  hydroxyl- 
amin  with  the  formation  of  amidosulfonic  acid  : 


Exercise  :  Convert  the  Tiydroxylamin  hydroehlorid  formed  in 
Preparation  22  into  amidosulfonie  acid. 

Operation:  Dissolve  the  hydroxylamin  hydrochlorid  in  a 
small  quantity  of  water,  and  lead  sulfur  dioxid  into  the  solu- 
tion for  a  long  time  (compare  page  56).  When  the  reaction  is 
completed,  the  solution,  on  cooling,  or  after  sufficient  concentra- 
tion on  the  water  bath,  deposits  crystals  of  amidosulfonic  acid. 
These  are  to  be  purified  from  the  hydroxylamin,  which  clings  to 
them  very  closely,  by  recrystallization. 

Properties  of  Amidosulfonic  Acid  :    Transparent,  rhombic 


AMIDOSULFONIC   ACID.  65 

crystals.  The  aqueous  solution  gives  no  precipitate  with  barium 
chlorid  (distinction  from  sulfuric  acid),  and  does  not  act  as  a 
reducing  agent.  When  boiled  with  the  addition  of  a  mineral 
acid  it  is  gradually  decomposed  with  the  formation  of  sulfuric 
acid  and  ammonia : 


TABLES 


MULTIPLES    OF   ATOMIC   WEIGHTS. 


69 


Multiples  of  the  Most  Frequently  Used  Atomic 
Weights  from  One  to  Five. 

(Bounded  off  to  the  whole  numbers.) 


1 

2 

3 

4 

5 

Aluminum  

Al 

27 

54 

81 

108 

135 

Antimony 

Sb 

120 

239 

359 

478 

598 

Barium  .    .    .  .          

Ba 

137 

274 

411 

548 

685 

Calcium  

Ca 

40 

80 

120 

160 

200 

Carbon  

c 

12 

24 

36 

48 

60 

Chlorin        . 

Cl 

35 

71 

106 

142 

177 

Copper  

Cu 

63 

126 

190 

253 

316 

Fluorin  

F 

19 

38 

57 

76 

95 

Iron  

Fe 

56 

112 

168 

224 

280 

Lead 

Pb 

206 

413 

619 

826 

1032 

Manganese  . 

Mn 

55 

110 

165 

220 

275 

]Sltrosren  

N 

14 

28 

42 

56 

70 

Oxygen  

o 

16 

32 

48 

64 

80 

Phosphorus 

p 

31 

62 

93 

124 

155 

Potassium 

K 

39 

78 

117 

156 

195 

Silicon     

Si 

28 

56 

85 

113 

141 

Silver  

Aa 

108 

215 

323 

431 

538 

Sodium 

Na 

23 

46 

69 

92 

115 

Sulfur      

S 

32 

64 

96 

128 

160 

Tin        

Sn 

118 

236 

354 

472 

590 

70    SPECIFIC  GRAVITY  OF  HYDROCHLORIC  AND  NITRIC  ACIDS. 

Specific  Gravity  of    Hydrochloric  Acid. 

(At  15°  C.) 


Sp.  Gr. 

Per  Cent.  HGl 
by  weight. 

Sp.  Gr. 

Per  Cent.  HGl 
by  weight. 

1.035     . 

7.1 

1.110    . 

....          21  9 

1.040 

8.1 

.115     . 

22  9 

1.045    . 

9.1 

.120    . 

23.9 

1.050    . 
.055    . 

10.0 
11.0 

.125     . 

24.8 

.130     . 
.135     . 
140 

25.8 
26.8 
27  8 

060 

12  0 

.065    . 
070 

13.0 
14  0 

145 

28  8 

075 

15  0 

150 

29  8 

080 

.     16  0 

.155 

30  8 

085    . 

169 

1  160 

.     .     31.8 

.090    . 
1.095    . 

.     .     .     •    .     17.9 
18.9 

1.165    . 

.     .     .     32.8 

1.170    . 

33.7 

1.100    . 

19.9 

1.175    . 

34.7 

1.105     . 

20.9 

1.180    . 

35.7 

Specific  Gravity  of   Nitric 

(At  15°  C.) 

Acid. 

Sp.  Gr. 

Per  Cent.  HNOZ 
by  weight. 

Sp.  Gr. 

Per  Cent.  HNO~A 
by  weight. 

1.200    . 

32.2 

1.360     . 
1.370     . 
1  380 

57.5 
59.3 

1.210     . 

.     .     .     33.8 

1  220 

35  4 

61  1 

1.230    . 
1.240    . 
1  250 

36.9 
38.4 
40  0 

1  390 

62  9 

1  400 

64  9 

1  410 

.     .     .     67.1 

1  260 

41  4 

1  420    . 

69.3 

1  270 

429 

1.430    . 

71.6 

1.280    . 
1.290 
1  300 

44.4 
45  9 

1.440    . 

74.4 

1  450 

.     77  3 

47  4 

1  460 

.     .     80  1 

1.310    . 
1.320     . 
1  330 

48.9 
50.5 
52  1 

1  470 

.     .     .     83.0 

1.480    . 

85.8 

1.490    . 

89.0 

1.340 
1.350 

.     53.9 

1.500    . 

92.3 

55  7 

1  510 

94  6 

SPECIFIC  GRAVITY  OF  SULFURIC  ACID  AND  AMMONIA.        71 

Specific  Gravity  of  Concentrated  Sulfuric  Acid. 

(At  15°  G) 


Sp.  Gr. 


Per  cent. 
by  weight. 

1.820 90.0 

1.825 91.0 

1.830 92.0 

1.835 93.5 

1.840 96.0 


NOTE.  The  specific  gravity  of  concentrated  sulfuric  acid  increases 
until  it  reaches  1.8413  where  it  contains  97.7  per  cent.  H.2SO^.  From  this 
point  the  specific  gravity  decreases  slightly,  and  there  corresponds  to 

98.0  per  cent,  by  weight  H2SO±,  the  specifics  gravity  1.8412 
99.0         "  "  "  "  "       1.8403 

100.0        "  "  "  "  "       1.8384 


Specific  Gravity  of  Ammonia. 

(At  15°  C.) 


Sp.  Gr. 

Per  Cent.  NH3 
by  weight. 

Sp.  Gr. 

Per  Cent.  JV#3 
by  weight. 

0  995 

1  0 

0.935 

16  9 

0  990 

2.1 

0.930  . 

18  3 

0  985 

...   3.3 

0.925  . 

19  8 

0  980  . 

....   4.5 

0.920  . 

...    21  3 

0  975 

....   5.7 

0.915  . 

....  22  8 

0  970 

7  0 

0  910 

24  4 

0  965 

8.4 

0.905 

26  0 

0  960 

...   9.8 

0.900 

27  7 

0  955 

....  11.2 

0.895  . 

.  .        29  5 

0  950 

....  12.6 

0.890  . 

.  .  .  .    31  4 

0  945  .  . 

....  14.0 

0.885  . 

33  4 

0  940 

15  4 

0  880 

35  5 

72 


SOLUBILITY   OF    CERTAIN    SALTS   IN   WATER. 


Solubility  of   Certain  Salts  in  Water. 

100  parts  water  dissolve  ?  grams. 


At 

0° 

10° 

20° 

40° 

60° 

80° 

100° 

Alum 

KA  1  (  S  04  )  2  ,  l£aq. 

3.9 

9.5 

15.1 

30.9 

66.6 

134.5 

357.5 

Ammonium  chlorid 

NHfil 

28.4 

32.8 

37.3 

46.2 

55.0 

63.9 

72.8 

Barium  chlorid 

BaCl^aq. 

41.5 

44.6 

.... 

59.1 

.... 

76.9 

Barium  hydroxid 

Ea(OH)2,8aq. 



4.7 

7.4 

16.4 

48.1 

3875 

... 

Barium  Nitrate 

Ba(N05}2 

1   5.2 

7.0 

9.2 

14.2 

20.3 

27.0 

32.2 

Copper  sulfate 

OuSO^aq. 

31.6 

37.0 

42.3 

56.9 

77.4 

118.0 

203.3 

Ferrous  sulfate 

FeSO,  7aq. 

.... 

61 

115 

227 

270 

at  24° 

at  46° 

at  84° 

Potassium  chlorid 

KG  I 

28.5 

32.0 

34.7 

40.1 

45.5 

51.0 

56.6 

Sodium  carbonate 

(dehydrated)  Na,COs 

.... 

12.6 

21.4 

38.1 

.... 

45.4 

at  30° 

Sodium  carbonate1  (crys- 

tallized) Na2C03,  lOaq. 

21.3 

40.9 

92.8 

273.6 

.... 

at  30° 

Sodium  phosphate2 

HNa,PO,,  ISaq. 

6.5 

10.5 

27.2 

4850 

.... 

1  Melts  at  34°  in  its  water  of  crystallization. 

2  Melts  at  a  little  above  35°  in  its  water  of  crystallization. 


'    **    jt  •**'•***'    •  t* 
SOLUBILITY    OF    CERTAIN    SALTS    IN    WATER/  "  73 


Solubility  of  Certain  Salts  in  Water. 

1  part  substance  requires  for  solution  ?  water. 


At 

0* 

10° 

20° 

40° 

60° 

80° 

100° 

Alum 

KAl(SO±),12aq. 

25.6 

10.5 

6.6 

3.2 

1.5 

0.74 

0.28 

Ammonium  chlorid 

NH^Cl 

3.5 

3.0 

2.7 

2.2 

1.8 

1.6 

1.4 

Barium  chlorid 

BaCl^aq. 



2.4 

2.2 

1.7 

1.3 

Barium  hydroxid 

Ba(  OH}^8aq. 

21.3 

13.5 

6.1 

2.1 

0.026 

Barium  nitrate 

Ba(N03)2 

19.2 

14.3 

10.9 

7.0 

4.9 

3.7 

3.1 

Copper   Sulfate 

CuSO^aq. 

3.2 

2.7 

2.1 

1.8 

1.3 

0.85 

0.49 

Ferrous  sulfate 

FeS04,7aq. 

.... 

1.6 

0.87 
at  24° 

0.44 
at  46° 

... 

0.37 

at  84° 

... 

Potassium  chlorid 

KCl 

3.5 

3.1 

2.9 

2.5 

2.2 

2.0 

1.8 

Sodium  carbonate 

(dehydrated)  JVa2C03 

.... 

7.9 

4.7 

2.6 

2.2 

2.2 

2.2 

at  30° 

Sodium  carbonate  (crys- 

tallized) Na^CO^  lOaq. 

4.7 

2.4 

1.1 

0.37 



at  30° 

Sodium  phosphate 

15.4 

9.5 

3.7 

0.021 

... 

UNIVERSITY  OF  CALIFORNIA  LIBRARY, 
BERKELEY 


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«W  80 1121 


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